Network switch, systems, and servers implementing boot image delivery

ABSTRACT

Methods, systems, and computer programs are presented for providing a program to a server. One method includes an operation for receiving a request by a switching device from a first server, the request being for a boot image for booting the first server. In addition, the method includes operations for determining if the boot image is available from non-volatile storage in the switching device, and for forwarding the request to a second server when the boot image is absent from the non-volatile storage. Further, the method includes an operation for sending the boot image to the first server from the switching device when the boot image is available from the non-volatile storage.

CLAIM OF PRIORITY

This application is a Continuation In-Part Application and claimspriority from U.S. application Ser. No. 13/313,837, entitled“DISTRIBUTED OPERATING SYSTEM FOR A LAYER 2 FABRIC,” and filed on Dec.7, 2011, which claims benefit under 35 U.S.C. §119(e) to U.S.Provisional Application Ser. No. 61/420,526, entitled “DISTRIBUTEDOPERATING SYSTEM FOR A LAYER 2 FABRIC,” filed on Dec. 7, 2010;

U.S. application Ser. No. 13/478,179, entitled “METHOD AND SYSTEM FORPROCESSING PACKETS IN A NETWORK DEVICE,” and filed on May 23, 2012,which claims benefit under 35 U.S.C. §119(e) to U.S. ProvisionalApplication Ser. No. 61/489,085 entitled “LOW LATENCY NETWORK FABRIC,”filed on May 23, 2011;

U.S. application Ser. No. 13/100,125, entitled “SWITCH FABRIC FORNETWORK DEVICES,” and filed on May 3, 2011, which claims benefit under35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 61/330,758,entitled “VIRTUAL NETWORKS,” filed on May 3, 2010, and U.S. ProvisionalApplication Ser. No. 61/346,138 entitled “NETWORK SWITCH,” filed on May19, 2010; and

U.S. application Ser. No. 13/099,918, entitled “METHOD AND SYSTEM FORRESOURCE COHERENCY AND ANALYSIS IN A NETWORK,” and filed on May 3, 2011,which claims benefit under 35 U.S.C. §119(e) to U.S. ProvisionalApplication Ser. No. 61/330,758, entitled “VIRTUAL NETWORKS,” filed onMay 3, 2010, and to U.S. Provisional Application Ser. No. 61/364,147entitled “VIRTUAL NETWORKS,” filed on May 19, 2010, and to U.S.Provisional Application Ser. No. 61/346,411, entitled “VIRTUALNETWORKS,” filed on May 19, 2010, all of which are incorporated hereinby reference.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related by subject matter to U.S. patent applicationSer. No. 13/842,619 filed on the same day as the instant application andentitled “Servers, Switches, and Systems with Switching ModuleImplementing a Distributed Network Operating System;” U.S. patentapplication Ser. No. 13,842,668 filed on the same day as the instantapplication and entitled “Servers, Switches, and Systems with VirtualInterface to External Network Connecting Hardware and IntegratedNetworking Driver;” U.S. patent application Ser. No. 13/842,867 filed onthe same day as the instant application and entitled “Methods andSystems for Managing Distributed Media Access Control Address Tables;”and U.S. patent application Ser. No. 13/842,806 filed on the same day asthe instant application and entitled “Methods, Systems, and Fabricsimplementing a Distributed Network Operating System,” all of which areincorporated herein by reference.

BACKGROUND

1. Field of the Invention

The present embodiments relate to systems, methods, and computerprograms for managing network traffic, and more particularly, systems,methods, and computer programs for implementing a distributed switchlayer fabric.

2. Description of the Related Art

The proliferation of network devices has resulted in complex networkingstrategies to distribute packets in a network efficiently. In somesolutions, multitier switching devices are used to build the network,but these complex multitier solutions do not provide an efficientdistribution of packets at the level 2, and the management of thesemultitier switches is difficult and inflexible.

In addition, with the exponential growth of virtual machines on thenetwork, the number of devices continues to grow exponentially. Theaddition of virtual networks, that include virtual machines and othernetwork devices, requires an efficient separation of traffic between thedifferent virtual networks, which is difficult to implement in themultitier switching architecture.

It is in this context that embodiments arise.

SUMMARY

Systems, devices, methods, and computer programs are presented forimplementing a distributed switch layer fabric. It should be appreciatedthat the present embodiments can be implemented in numerous ways, suchas a method, an apparatus, a system, a device, or a computer program ona computer readable medium. Several embodiments are described below.

In one embodiment, a networking device system is provided. Thenetworking device system includes a switch module, a server, and aswitch controller. The switch module has one or more ports with acommunications interface of a first type (CI1) and one or more portswith a communications interface of a second type (CI2). The server is incommunication with the switch module via a first CI2 coupling, andincludes a virtual CI1 driver that provides a CI1 interface toapplications in the server, the virtual CI1 driver defined to exchangeCI1 packets with the switch module via the first CI2 coupling. Thevirtual CI1 driver includes a first network device operating system(ndOS) program. The switch controller is in communication with theswitch module via a second CI2 coupling, and includes a second ndOSprogram that, when executed by a processor, controls packet switchingpolicy in the switch module, the packet switching policy includingdefinition for switching incoming packets through the switch module orthrough the switch controller. The first ndOS program and the secondndOS program, when executed by respective processors, exchange controlmessages to maintain a network policy for a switch layer fabric.

In another embodiment, a networking device system includes a switchmodule, a plurality of servers, and a switch controller. The switchmodule has one or more ports with a communications interface of a firsttype (CI1) and one or more ports with a communications interface of asecond type (CI2). Further, the plurality of servers is in communicationwith the switch module via a first CI2 couplings, the servers includinga respective virtual CI1 driver that provides a CI1 interface toapplications in the respective server, each virtual CI1 driver definedto exchange CI1 packets with the switch module via the first CI2coupling, and each virtual CI1 driver further including a first networkdevice operating system (ndOS) program. The switch controller is incommunication with the switch module via a second CI2 coupling, and theswitch controller includes a second ndOS program that, when executed bya processor, controls packet switching policy in the switch module. Thepacket switching policy includes a definition for switching incomingpackets through the switch module or through the switch controller,where the first ndOS program and the second ndOS program, when executedby respective processors, exchange control messages to maintain anetwork policy for a switch layer fabric.

In yet another embodiment, a method for processing packets includes anoperation for receiving a packet at a switch module, the switch modulehaving one or more ports with a communications interface of a first type(CI1) and one or more ports with a communications interface of a secondtype (CI2). Further, a server is in communication with the switch modulevia a first CI2 coupling, and a switch controller is in communicationwith the switch module via a second CI2 coupling. The server includes avirtual CI1 driver that provides a CI1 interface to applications in theserver, the virtual CI1 driver defined to exchange CI1 packets with theswitch module via the first CI2 coupling. The virtual CI1 driver furtherincludes a first network device operating system (ndOS) program, and theswitch controller including a second ndOS program that, when executed bya processor, controls a packet switching policy in the switch module,the packet switching policy including a definition for switchingincoming packets through the switch module or through the switchcontroller. The first ndOS program and the second ndOS program, whenexecuted by respective processors, exchange control messages to maintaina network policy for a switch layer fabric. Further, the method includesan operation for determining by a classifier in the switch module toswitch the packet through the switch module or through the switchcontroller based on the packet switching policy. The method includesanother operation for switching the packet based on the determining.

In one embodiment, a method for networking communications is provided.The method includes an operation for receiving a packet in a firstformat by a virtual driver providing a communications interface of afirst type (CI1), the first format being for CI1. In addition, themethod includes an operation for encapsulating the packet in a secondformat by a processor, the second format being for a communicationsinterface of a second type (CI2) different from CI1. Further, the methodincludes an operation for sending the encapsulated packet in the secondformat to a switch module. The switch module includes a switch fabric,one or more CI1 ports and one or more CI2 ports, where the switch moduletransforms the packet back to the first format to send the packet in thefirst format to a CI1 network via one of the CI1 ports in the switchmodule. In one embodiment, the operations of the method are executed bya processor.

In another embodiment, a networking device system includes a switchmodule and a server. The switch module has one or more ports with acommunications interface of a first type (CI1), one or more ports with acommunications interface of a second type (CI2), and a switch fabric.The server is in communication with the switch module via a first CI2coupling, and the server includes a virtual CI1 driver that provides aCI1 interface to applications in the server. The CI1 packets sent fromapplications in the server to the virtual CI1 driver are encapsulated inCI2 format before being transmitted to the switch module, where theswitch module transforms the encapsulated packets into CI1 format beforesending the packets to a CI1 network through one of the CI1 ports.

In yet another embodiment, a computer program embedded in anon-transitory computer-readable storage medium, when executed by one ormore processors, for networking communications, includes programinstructions for receiving a packet in a first format by a virtualdriver providing a communications interface of a first type (CI1), thefirst format being for CI1. In addition, the computer program includesprogram instructions for encapsulating the packet in a second format,the second format being for a communications interface of a second type(CI2) different from CI1. Further, the computer program includes programinstructions for sending the encapsulated packet in the second format toa switch module. The switch module includes a switch fabric, one or moreCI1 ports and one or more CI2 ports, and the switch module transformsthe packet back to the first format to send the packet in the firstformat to a CI1 network via a CI1 port in the switch module.

In one embodiment, a method for providing a program to a server isprovided. The method includes an operation for receiving a request by aswitching device from a first server, the request being for a boot imagefor booting the first server. Additionally, the method includesoperations for determining if the boot image is available fromnon-volatile storage in the switching device, and for forwarding therequest to a second server when the boot image is absent from thenon-volatile storage. Further, the method includes an operation forsending the boot image to the first server from the switching devicewhen the boot image is available from the non-volatile storage. In oneembodiment, the operations of the method are executed by a processor.

In another embodiment, a switching device includes a non-volatile memoryhaving one or more boot images, a volatile memory having a computerprogram, a switch fabric, and the processor. The processor is coupled tothe non-volatile memory, the volatile memory, and the switch fabric. Thecomputer program, when executed by the processor, performs a methodhaving an operation for receiving a request by the switch fabric from afirst server, the request being addressed to a second server, and therequest being for a first boot image for the first server. Additionally,the method includes operations for determining if the first boot imageis available in non-volatile memory, and for forwarding the request tothe second server when the boot image is absent from the non-volatilememory. Further yet, the method includes an operation for sending thefirst boot image to the first server when the first boot image isavailable from the non-volatile memory.

In one embodiment, a network device operating system (ndOS) programembedded in a non-transitory computer-readable storage medium, whenexecuted by one or more processors, for managing a switching layerfabric, is provided. The ndOS program includes program instructions forexchanging switching policy regarding a switching of network packets ina plurality of ndOS switching devices having respective ndOS programsexecuting therein, where the first ndOS program is executed in a firstndOS switching device, and the switching policy is exchanged with otherndOS programs via multicast messages. The ndOS program further includesprogram instructions for exchanging resource control messages with theother ndOS switching devices to implement service level agreements inthe switching layer fabric, where the ndOS switching devices cooperateto enforce the service level agreements. In addition, the ndOS programfurther includes program instructions for receiving changes to theswitching policy, and program instructions for propagating the receivedchanges to the switching policy via message exchange between the ndOSprograms. The ndOS switching devices are managed as a single logicalswitch that spans the plurality of ndOS switching devices.

In another embodiment, a method for managing a switching layer fabric isprovided. The method includes an operation for exchanging, by a firstndOS program executing in a first ndOS switching device, a switchingpolicy regarding a switching of network packets in a plurality of ndOSswitching devices. Each ndOS switching device has a respective ndOSprogram executing therein, where the switching policy is exchanged withother ndOS programs via multicast messages. In addition, the methodincludes an operation for exchanging resource control messages with theother ndOS switching devices to implement service level agreements inthe switching layer fabric, where the ndOS switching devices cooperateto enforce the service level agreements. Further, the method includesoperations for receiving changes to the switching policy, and forpropagating the received changes to the switching policy via messageexchange between the ndOS programs, where the ndOS switching devices aremanaged as a single logical switch that spans the plurality of ndOSswitching devices.

In yet another embodiment, a network device operating system (ndOS)switching device includes a processor, a switch fabric connected to theprocessor, and the memory. The memory has a first ndOS program that,when executed by the processor, performs a method, the method includingan operation for exchanging a switching policy regarding a switching ofnetwork packets in a plurality of ndOS switching devices, each ndOSswitching device having a respective ndOS program executing therein,where the switching policy is exchanged with other ndOS programs viamulticast messages. In addition, the method includes an operation forexchanging resource control messages with the other ndOS programs toimplement service level agreements in the switching layer fabric, wherethe ndOS switching devices cooperate to enforce the service levelagreements. Further, the method includes operations for receivingchanges to the switching policy, and for propagating the receivedchanges to the switching policy via message exchange between the ndOSprograms, where the ndOS switching devices are managed as a singlelogical switch that spans the plurality of ndOS switching devices.

Other aspects will become apparent from the following detaileddescription, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments may best be understood by reference to the followingdescription taken in conjunction with the accompanying drawings.

FIGS. 1A-1B illustrate the architecture of a distributed network deviceoperating system (ndOS), according to one embodiment.

FIG. 2 shows a layer 2 fabric in accordance with one or moreembodiments.

FIG. 3 illustrates a multitier fabric architecture, according to oneembodiment.

FIG. 4 shows an example of resource coherency and analytics controlengine interacting to manage packet traffic across multiple switches,according to one embodiment.

FIG. 5 shows a network device in accordance with one or moreembodiments.

FIG. 6 illustrates an exemplary embodiment of a network device.

FIG. 7 illustrates resource coherency and analytics engines inaccordance with one or more embodiments.

FIG. 8 is a flowchart of an algorithm for processing packets received bya virtual traffic shaper (VTS) in accordance with one or moreembodiments.

FIGS. 9A-9H illustrate sample embodiments of a switch module coupled toone or more servers and a switch controller.

FIGS. 10A-10B illustrate a networking software architecture in a server,according to one or more embodiments.

FIGS. 11A-11B illustrate the interactions between the hypervisor and thendOS, according to one or more embodiments.

FIGS. 12A-12B illustrate a multilevel distributed MAC tablearchitecture, according to one or more embodiments.

FIG. 13 is a flowchart of a method for managing a distributed MAC table,according to one or more embodiments.

FIG. 14 is a data structure for a MAC table, according to one or moreembodiments.

FIG. 15 is a simplified schematic diagram of a computer system forimplementing embodiments described herein.

FIGS. 16A-16D illustrate exemplary embodiments of a distributed ndOS,according to one or more embodiments.

FIG. 17A shows a flowchart illustrating an algorithm for processingnetwork packets, in accordance with one embodiment.

FIG. 17B shows a flowchart illustrating an algorithm for networkingcommunications, in accordance with one embodiment.

FIG. 17C shows a flowchart illustrating an algorithm for switching anetwork packet, in accordance with one embodiment.

FIG. 17D shows a flowchart illustrating an algorithm for providing aprogram to a server, in accordance with one embodiment.

FIG. 17E shows a flowchart illustrating an algorithm for managing aswitching layer fabric, in accordance with one embodiment.

DETAILED DESCRIPTION

The following embodiments describe systems, devices, methods, andcomputer programs for a distributed network device operating system(ndOS). It will be apparent, that the present embodiments may bepracticed without some or all of these specific details. In otherinstances, well known process operations have not been described indetail in order not to unnecessarily obscure the present embodiments.

FIGS. 1A-1B illustrate the architecture of a distributed Network DeviceOperating System (ndOS), according to one embodiment. The networkenvironment of FIG. 1A includes a rack 102 with a plurality of servers112, storage devices 116, power supplies 114, etc. In addition, rack 102includes a switch 104.

Switch 104 includes an instance of the ndOS, permanent storage 110, anda plurality of Ethernet ports 106 (more details regarding the componentsof switch 104 are given below with reference to FIGS. 5-7, 9A-9H, andothers). The ndOS is a distributed network device operating system thatspans a plurality of layer-2 devices (e.g., switches) across thenetwork. The ndOS is also referred to herein as network operatingsystem, networking operating system, layer-2 operating system, ordistributed switching operating system. The interconnected switches withndOS provide what appears to be a single logical switch that spans aplurality of switches, even switches located in geographically separateddata centers 120 a and 120 b. The switches with ndOS build a layer-2fabric that expands beyond a single switch and a single data center. Asused herein, switching devices with ndOS are also referred to herein asndOS switches or server-switches.

As used herein, layer 2, named the data link layer, refers to the secondlayer of the OSI network model. In addition, it is noted that althoughthe switches are described with reference to a layer 2 implementation,other layers in the OSI model may also be utilized to interconnectswitches (e.g., remote switches may be connected via tunneling using anInternet protocol (IP) network), and some of the operations performed bythe switches may expand into other layers of the OSI model. The layer 2fabric is also referred to herein as the switch layer fabric or thelayer 2 switch fabric.

The conceptual use of a single layer 2 fabric allows the creation ofapplication specific flows and virtual networks with hardware-basedisolation and hardware-based Service Level Agreements (SLAs). The scopeof virtual networks and application flows can be restricted toindividual switches (or ports within a switch) or can be extended toswitch clusters and entire layer 2 fabrics. As a result, end-to-endresource management and guaranteed SLAs are provided.

In one embodiment, the ndOS manages the physical network boxes and thefabric (the collection of ndOS instances) of ndOS switches like ahypervisor manages an individual server. The ndOS can spawn isolatednetworks with guaranteed performance levels that are virtuallyindistinguishable from an application point of view, from a physicalnetwork. This functionality is similar to how a hypervisor spawnsvirtual machines that look and act as physical machines.

Switch management tools allow network administrators to manage thecomplete layer-2 fabric—such as viewing, debugging, configuring,changing, setting service levels, etc.—including all the devices in thelayer-2 fabric. For example, individual switches may come online andautomatically join the existing fabric. Once in the fabric, devices canbe allocated into local, cluster, or fabric-wide pools. In a given poolof switches, resource groups (physical and virtual servers and virtualnetwork appliances) are managed with defined policies that includedefinitions for bandwidth, latency, burst guarantees, priorities, droppolicies, etc.

The ndOS, and the ndOS switches, may create application flows andvirtual networks on the fabric. SLAs (e.g., access control lists (ACL),VLAN tags, guaranteed bandwidth, limits on bandwidth, guaranteedlatency, priority on shared resources, performance of network servicessuch as firewalls and load balances and others, etc.) become attributesof each application flow or virtual network. These attributes aremanaged by the network operating system, and virtual machines are freeto communicate within the scope of their virtual networks.

In one embodiment, as described in more detail below, the ndOS switchesinclude a switch fabric, a processor, permanent storage, and networkpacket processors, which enable massive classification and packetcopying at line rates with no latency impact. The network operatingsystem may dynamically insert probes with no hardware or physicalreconfiguration at any point in the fabric and copy full or filteredpacket streams to the ndOS itself with meta-information such asnanosecond level timestamps, ingress port, egress port, etc. As aresult, fabric-wide snooping and analytics are both flexible and with noimpact on performance.

In one embodiment, the ndOS captures streams (e.g., 40 Gbps per ndOSswitch) and stores them on non-volatile storage (e.g., 1 terabyte).Rolling logs permit post-processing and re-creation of entireapplication flows across the fabric. The ndOS is also able to tracklink-level latency of each application and virtual network along withadditional comprehensive statistics. In one embodiment, the statisticsinclude which machine pairs are communicating, connection life-cyclesbetween any machines, packet drops, queuing delays, etc. The networkoperating system tracks fine-grained statistics and stores them inpermanent storage to permit inspection of history at a point in time orover a period of time. Further, the probe points may implement countersor copy the packets without adding any latency to the original stream,or the probes may increment double-buffered counters which can be directmemory mapped into the network operating system and allow userapplications running on the switch to make real time decisions.

In one embodiment, the ndOS is also a hypervisor and thus can runstandard network services like load balancers, firewalls, etc. Further,the ndOS allows switches to discover other switches. In one embodiment,all ndOS instances know about each other using a multicast-basedmessaging system. In one embodiment, ndOS switches periodically sendmulticast messages on a well-known address, the multicast messagesincluding the senders' own IP address and a unique switch identifier(ID). In one embodiment, this multicast message is also utilized as akeep-alive message.

In addition, ndOS switches may create direct connections with each otherto reliably exchange any information. Each ndOS instance keeps track ofthe local configuration information but also keeps track of globalinformation (e.g., MAC address tables). An administrator is able toconnect to any ndOS instance (using ndOS provided applicationprogramming interfaces (API) and other interfaces) and configure anyparticular switch, or change the global configuration or resourcepolicies, which are reliably communicated to other ndOS instances in thefabric using a two-phase commit, or some other procedure. In phase 1 ofthe two-phase commit, resources are reserved and in phase 2 resourcesare committed. From the management perspective, the administrator has aglobal view of the entire layer-2 fabric and is able to apply local orglobal configuration and policies to any ndOS instance.

In one embodiment, the ndOS also enables administrators to configurenotification of events related to changes in the fabric (e.g., switchesbeing added or deleted), changes in link status, creation of virtualmachines (VMs), creation, deletion, or modification of a network-hostedphysical or virtual storage pool, etc. The clients can interact with anndOS instance on a local switch, or on any switch in the fabric. Thefabric itself reliably ensures that one or more switches get configuredappropriately as needed.

FIG. 1B illustrates the integrated layer-2 fabric architecture,according to one embodiment. A plurality of machines in physical rackscan map onto a set of virtual networks that carve out portions of asingle massive logical switch constructed out of the network fabric.

Each instance of the ndOS also communicates with other ndOS switches tokeep a global state of flows, services, and virtual networks in thefabric. Resource and congestion management policies on individualswitches and line cards ensure that each application flow, service, orvirtual network benefit across the fabric and not just within individualswitches.

In one embodiment, individual ndOS instances have line cards, datastructures, and counters which enable having real time information tomake real-time decisions as to application flows, services, and virtualnetworks (more details are provided below with reference to FIGS. 5 and6). The deep packet buffers and processing capability allow the networkoperating system to shape individual application flows (for example aburst of packets for an application flow may be buffered and forwardedover a longer time period at a constant bandwidth or a criticalapplication flow can be bypass a queue of less important packets toachieve lower latency, etc.), and virtual networks based on configuredSLA and match network resources across the fabric to their needs.

The ndOS layer-2 fabric 134 appears as one huge logical switch that canbe managed in whole (e.g., using ndOS controller 132). The ndOScontroller 132, or the network management platform 130 whichcommunicates with the ndOS controller 132, can create virtual networksthat span the entire fabric, clusters, etc. Each cluster gets its owncluster manager in the form of a virtual machine that has privileges toperform cluster related operations. For instance, cluster managers cancreate virtual networks whose scope is local to a switch within thecluster. Alternatively, the scope may be across all members of theclusters. The cluster manager can also control the resources within thecluster (as specified by the ndOS controller 132). In one embodiment,each virtual network gets its own virtual network manager in the form ofvirtual machines that are hosted on one of the ndOS switches.

In one embodiment, the ndOS switches are programmable using C, Java, andhtml APIs (or other programs and protocols) that allow user applicationsto run on hosts or on the ndOS switch and gain access to low-leveldetails, probe insertion and packet capture, configuring events, etc.The network operating system also uses emerging standards like OpenFlow,OpenStack, VMware, etc. to access a subset of this information in otherways.

In one embodiment, the ndOS is managed via a graphical user interface,or a text driven interface, or computer generated API calls, etc. Forexample, an administrator may request from the network managementplatform 130 a certain number of IP addresses, a certain networkconfiguration with switches and routers, non-redundant IP address, etc.

It is noted that the embodiments illustrated in FIGS. 1A and 1B areexemplary. Other embodiments may utilize different topologies,configuration, have a mixture of devices with ndOS and without ndOS,etc. The embodiments illustrated in FIGS. 1A and 1B should therefore notbe interpreted to be exclusive or limiting, but rather exemplary orillustrative.

FIG. 2 shows a layer 2 fabric in accordance with one or moreembodiments. In one embodiment, the layer 2 fabric includes four networkdevices (network devices 1-4), and each network device includes an ndOSthat is defined to determine the layer 2 topology of the layer 2 fabric.

In the example shown in FIG. 2, network device 1 is directly connectedto network device 2 and network device 4, and is indirectly connected tonetwork device 3. Network device 2 is directly connected to networkdevice 1 and network device 3, and is indirectly connected to networkdevice 4. Network device 3 is directly connected to network device 2 andis indirectly connected to network device 1 and network device 4.Finally, network device 4 is directly connected to network device 1 andis indirectly connected to network devices 2 and 3. A given networkdevice may communicate directly with any directly connected networkdevice and may use other network devices in the layer 2 fabric tofacilitate indirect communication with indirectly connected networkdevices. Not shown, but also within the scope of this invention are theuse of any network of non-ndOS network device between any pair ofnetwork devices 1 to 4. In this case the non-ndOS network devices willforward packets using conventional Ethernet protocols, but the NetworkDevices 1 to 4 will in-effect be tunneling through the non-Layer 2Fabric to join non-directly connected Layer 2 Fabrics into whatin-effect acts like a directly connected Layer 2 Fabric.

In one embodiment, each ndOS is configured to monitor the network deviceon which it is executing to determine if (or when) there is a change inthe local configuration information. If there is a change in the localconfiguration information, the ndOS is configured to communicate all (ora subset of) the updated local configuration information directly orindirectly to all of the other ndOS instantiations in the layer 2fabric.

In one embodiment, a client executing on any host connected to anynetwork device in the layer 2 fabric may initiate a request (describedabove) to the layer 2 fabric. In such cases, the request may beinitially received by the closest ndOS to the host. For example, if hostH5 issued a request to the layer 2 fabric, the request may be initiallyreceived by ndOS 4. Based on the nature of the request, ndOS 4 may sendthe request to one or more of the ndOS instances in the layer 2 fabricto process the request. In one embodiment, the client making the requesthas full visibility of the layer 2 fabric and, as such, can issuerequests to any network entity in or connected to the layer 2 fabric.

In one embodiment, the request may include, but is not limited to, (i) arequest to migrate a virtual machine (VM) from one host to another host,where both hosts are connected to the layer 2 fabric; (ii) a request tochange an ACL for a given network entity, where the network entity isconnected to the layer 2 fabric via a network device that is part of thelayer 2 fabric; (iii) a request to perform analytics on a flow that ispassing through at least one network device in the layer 2 fabric; (iv)a request to create a VM on a particular network device in the layer 2fabric; (v) a request to create a VM on a host connected to a networkdevice in the layer 2 fabric; (vi) a request to change a configurationparameter on a particular network device in the layer 2 fabric; (vii) arequest to change a configuration parameter on two or more networkdevices in the layer 2 fabric; and (viii) a request to create anotification when there is a change in the layer 2 fabric (e.g., networkdevice added, network device removed, change in link status of a linkbetween network devices in the layer 2 fabric, creation of a VM on anetwork device in the layer 2 fabric, etc.), automatically detected VMmigrations that were not directly notified to the fabric (for examplebased on noting a new physical port P1, P2, or P3 in this diagram thatis carrying packets that can be recognized to originate from a given VM)and applying certain policy such as automatically move resourcepolicies, notifying some other program, etc. The requests may includeother actions to be performed not specified above without departing fromthe embodiments.

In one embodiment the request may be for performing analytics. Therequest to perform analytics may include a request to obtain all packetsfor a given flow (or set of flows), where the flow is passing throughone network device on the layer 2 fabric. Because the layer 2 fabricincludes a network distributed operating system (ndOS), a request toobtain all packets for a given flow may be received by any ndOS in thelayer 2 fabric. The ndOS that receives the request will forward therequest to the appropriate network device. In another embodiment, therequest is to obtain all packets for a given flow (or set of flows), andthe request is forwarded to a network device (referred to as monitoringnetwork device) through which the flow passes. The monitoring networkdevice may program its switch fabric classifier to identify all packetsfor the flow and to send all identified packets to the control processor(or to the network processing unit (NPU)). Upon receipt the controlprocessor (or NPU) may make a copy of the packet. The monitoring networkdevice may accumulate the copies of the packets and then subsequentlytransmit (via the network devices in the layer 2 fabric) the copies ofthe packets to the ndOS that initially received the request. Uponreceipt, the ndOS may forward the copies of the packets to the host fromwhich the request was received. Alternatively, the monitoring networkdevice may store the accumulated copies on local storage, or transmitthem to one more network device in the Layer 2 Fabric and device outsidethe Layer 2 Fabric for combination of storage or analysis.

FIG. 3 illustrates a multitier fabric architecture, according to oneembodiment. The ndOS provides for the creation of different types ofVirtual Networks 152, 154, 156, 158 (VNs, or vNets) and the assignmentof resources and policies to the virtual networks, in one embodiment. Insome sense, a vNet is not the same as an IEEE 802.1q VLAN, but instead,the 802.1q VLAN tag is just one of the possible attributes of the ndOSvirtual network. The vNet is a collection of Virtual Machines,identified, for example, by their one or more MAC addresses, IPaddresses, physical ports, etc., and has network attributes like VLANtag, QoS labels, etc., associated therewith. In addition, the vNet alsodefines network resources like bandwidth guarantees, limits, latencyranges, queues, isolation semantics (in the form of virtual outputqueues, ingress and egress queues, etc.), number and performance andresource of virtual network services, etc. The scope of a vNet can berestricted to an individual switch (referred to as a local vNet) in thefabric, or to a cluster of switches (referred to as a cluster vNet) inthe fabric, or to the entire fabric (global vNet).

In case where the host management is done by separate managementsoftware, ndOS provides APIs for external clients and agents to querythe vNet information and its scope. Further, when the external agent orhost management software wants to migrate a VM, the agent or host canquery any ndOS instance to get a list of physical hosts which areallowed to host the virtual machine based on the scope of the vNet.

The ndOS extends the reach of the programmable layer 2 fabric when thehosts have virtualization-enabled network interface controller (NICs).Many modern NICs have some kind of virtualization support, for examplebuilt in the form of SR-IOV (Single root I/O Virtualization), an IEEEstandard. This allows individual VMs to obtain part of the NICresources, and the NIC itself appears directly mapped into the virtualmachine. In one embodiment, the VM is directly able to communicate onthe wire without its packets going through the hypervisor. This is goodfor performance but causes issues related to the informant of ACLs andbandwidth allotments. Even if a network interface card (NIC) provides amechanism for ACL and bandwidth enforcements, the host administrator hasto manually configure this parameters for the VM on the host.

Often times, a collection of VMs on different hosts belong to the samevirtual network and need similar configuration. If the administrator hasto configure each VM manually on each host, this configuration processis prone to human error. In addition, the VM cannot migrate dynamicallybecause the administrator has to manually configure the same policy onthe target host before allowing the VM to migrate. As shown in FIG. 3,by allowing the ndOS on the switch to control the NIC on the host(either via a dedicated control port, hypervisor APIs or an ndOS agentrunning on the hypervisor), ndOS can automatically configure the ACL andany bandwidth limits/guarantees on the NIC on the target host based onthe overall policies specified for the vNet. This allows the VMs todynamically migrate without any violation of SLA or security policies.

In addition to managing ACL and bandwidth guarantees and limits on aper-VM basis on individual hosts, ndOS can automatically configurepriority based flow control (IEEE 802.1 Qbb); Enhanced TransmissionSelection (IEEE 802.1 Qaz); Edge Virtual Bridging (802.1 Qbg); Layer 2Congestion Notification (802.1 Qau), etc., for individual VMs based onthe overall policies specified for the vNet or by the vNetadministrator. For instance, the fabric or cluster administrator mayspecify that all VM-to-VM communication needs to be accounted on theswitch, which would result in ndOS configuring each host NIC to disableVM switching, and instead forward all packets to the first hop switch.In another instance, ndOS would configure any ACL specified for the vNeton all hosts that have a member VM for that particular vNet. The vNetadministrator may be given privileges to ask ndOS to assign EmergencyTelecommunications Service (ETS) labels to different traffic types forits member VMs in which case ndOS will configure the NICs on all hoststhat support a VM belonging to the particular vNet. As the VMs migrate,the VNIC (and any VLAN) configuration is automatically instantiated onthe target host and NIC by ndOS.

NdOS supports management of VMs on the hosts and can directly controlthe VM migration, including moving the necessary attributes like ACL,bandwidth guarantees/limits, etc. on the target system before migratingthe VM. NdOS also supports a split management model where a hostmanagement system triggers the migration of VMs to a target system. Whenthe VM sends out an ARP packet on the receiving host, ndOS automaticallyrecognizes the MAC address and the fact that the host has not seen theMAC address on that particular switch port. NdOS then figures out theold host for the moving VM, which can be connected on another port or toanother switch, and then moves the attributes corresponding to the VMfrom the NIC on the original host to the NIC on the target host. SincendOS is a distributed operating system and all instances share allnecessary information, ndOS can support VM migration across any switchin the L2 fabric as long as the VM is allowed, based on the policy givento the ndOS, to migrate to the target host based on the scope of thevNet.

In one embodiment, the ndOS switch also supports virtual network machine(VNM) appliances such as load balancers, firewalls, or customer specificappliances, as well as deep analytic appliances for compliance,Distributed Denial of Service (DDoS) monitoring, etc.

In summary, the multi-tier fabric 134 appears as a universal logicalswitch, which means dynamic and flexible partition with full isolation,and instantiation of virtual appliances and virtual machines in thevirtual networks created in the layer-2 fabric.

FIG. 4 shows an example of resource coherency and analytics controlengines interacting to manage packet traffic across multiple switches,according to one embodiment. For purposes of this example, it is assumedthat hosts A, B, and C belong to the same virtual resource group (VRG)and, as such, are allowed to communicate with each other. Further, it isalso assumed that hosts A and B are both sending packets to host C viaswitch D, and that the egress physical port (EPP) on switch B, that isconnected to Switch D, is close to reaching its limited bandwidth (asdefined by the virtualizable resource control list (VRCL) associatedwith the VRG).

Using Resource Coherency and Analytics engine (RCAE) statistics for RCAEB and a bandwidth notification threshold (i.e., a threshold above whichthe RCAE issues bandwidth control messages), RCAE B determines that thebandwidth notification threshold has been exceeded. The bandwidthnotification threshold may be based on the depth of one or more of thevirtual output queues (VOQ) associated. Alternatively, the bandwidthnotification threshold may be deemed to be exceeded when RCAE Binstructs the VTS to stop scheduling the packets in the VOQ fortransmission or instructs the VTS to decrease a rate at which the VTSschedules the packets in the VOQ for transmission. Alternatively, thebandwidth notification threshold may be deemed to be exceeded if RCAE Bdetermines that the average number of bytes or packets has exceeded somethreshold over one or more timespans with some uniform or non-uniformmoving average. Those skilled in the art will appreciate that thebandwidth notification threshold may be based on other metrics withoutdeparting from the embodiments.

In response to this determination, RCAE B reduces the drain rate for theEPP connected to switch D to prevent the EPP from reaching the limitedbandwidth as specified in the VRCL. In addition, the above determinationtriggers the RCAE B to issue bandwidth control messages (BCM) to switchC and switch A. In one embodiment, the BCM to switch A includes, but isnot limited to, information to identify the VRG associated with the VOQon RCAE B that triggered the issuance of the BCM, information toidentify the EPP on RCAE B (i.e., the EPP on switch C connected toswitch D), information about the current depth of the VOQ in RCAE B ofthe VTS that processes packets received from switch A, and a recommendeddrain rate for the EPP in RCAE A that is connected to switch B.

Similarly, the BCM to switch C includes, but is not limited to,information to identify the VRG associated with the VOQ on RCAE B thattriggered the issuance of the BCM, information to identify the EPP onRCAE B (i.e., the EPP on switch C connected to switch D), informationabout the current depth of the VOQ in RCAE B of the VTS that processespackets received from switch C, and a recommended drain rate for the EPPin RCAE C that is connected to switch B.

In one embodiment, the BCMs are transmitted to the appropriate switchesusing an out-of-band communication channel, i.e., a communicationchannel or connection that is different than the communication channelused to communicate packets between the switches.

In response to receiving the BCM from switch B, RCAE A in switch A mayupdate one or more operating parameters in RCAE A. For example, theoperating parameters for the VTS in RCAE A that is receiving packetsfrom host A may be updated to decrease its drain rate for the EPPconnected to switch B. In another embodiment, the vCoherence Controller(VCC) in RCAE A receives the BCM and updates the drain rate for the VOQsdraining to the EPP on RCAE that is transmitted packets to Switch B. Inone embodiment, the drain rate calculated for a VOQ using both RCAEstatistics from RCAE A and the BCM from switch B is less than the drainrate calculated using on the RCAE statistics. Said another way, the VCCmay use the BCM to further decrease the drain rate for a given VOQ, eventhough the RCAE statistic would allow for a higher drain rate. Inanother embodiment, RCAE A may requested by the BCM from switch B todrop a certain number of packets picked randomly or by deterministicorder or by some flow classification, and may also request that certainflows are not dropped and have changes in their latency policies to meetsome Layer 2 Fabric latency SLA, for example, etc. Other types of BCMmessages may be used depending on how switch B determines to bestcontrol the bandwidth.

Further, switch A may issue a pause-control-frame (PCF) as defined byIEEE 802.3x or any other standard to host A. The PCF may request host Ato decrease the rate at which host A sends packets to switch A.

In response to receiving the BCM from switch B, RCAE C in switch C mayupdate one or more operating parameters in RCAE C. For example, theoperating parameters for the VTS in RCAE C that is receiving packetsfrom host C may be updated to decrease its drain rate for the EPPconnected to switch B.

Each Resource Coherency and Analytics engine (RCAE) is configured tocollect RCAE statistics. The RCAE statistics may be used to determine around-trip delay of packets transmitted through a switch that includesan RCAE. In one or more embodiments, the RCAE uses the clock on theswitch to calculate round-trip delays. The round-trip delay may bedetermined for both connection and connection-less protocols. Moredetails regarding the implementation of RCAE are provided below withreference to FIGS. 15 and 16A-16D.

FIG. 5 shows a network device in accordance with one or moreembodiments. In one or more embodiments, the network device 104 includesexternal ports 176, internal ports 174, a switch fabric classifier 178,one or more network processing units (NPUs) 172A-172B, also referred toherein as packet processors, a control processor 162, persistent memory164, a Peripheral Component Interconnect Express (PCIe) switch 170,switch fabric 180 and volatile memory 166.

In one embodiment, the network device 104 is any physical device in anetwork that includes functionality to receive packets from one networkentity and send packets to another network entity. Examples of networkdevices include, but are not limited to, single-layer switches,multi-layer switches, and routers. Network entities correspond to anyvirtual or physical device on a network that is configured to receivepackets and send packets. Examples of network entities include, but arenot limited to, network devices (defined above), virtual machines, hostoperating systems natively executing on a physical device (also referredto as hosts, see, e.g., 102A, 102B), virtual network appliances (e.g.,virtual switch, virtual router), and physical network appliances (e.g.,firewall appliance).

The network device 104 (or components therein) may be implemented usingany combination of hardware, firmware, and/or software. With respect tothe hardware, the network device may be implemented using anycombination of general purpose hardware and/or special purpose hardware(e.g., Field Programmable Gate Arrays (FPGAs), Application SpecificIntegrated Circuits (ASICs), etc.) and any type of storage and/or memoryincluding, but not limited to, random access memory (RAM), dynamicrandom access memory (DRAM), static random access memory (SRAM),NAND-type flash memory, NOR-type flash memory, any other type of memory,any other type of storage, or any combination thereof.

In one embodiment, the switch fabric 180 includes one or more internalports 174, one or more external ports 176, and the switch fabricclassifier 178. In one embodiment, the switch fabric classifier 178 maybe implemented using an on-chip or off-chip Ternary Content AddressableMemory (TCAM) or other similar components. In one embodiment, theinternal and external ports correspond to virtual or physical connectionpoints. In one embodiment, the switch fabric may be implemented usingpacket switching, circuit switching, another type of switching, or anycombination thereof. The external ports 176 are configured to receivepackets from one or more hosts 162A-162B and to send packets to one ormore hosts 162A-162B. While FIG. 5 shows the external ports connectedonly to hosts 162A-162B, the external ports 176 may be used to send andreceive packets from any network entity.

In one embodiment, the internal ports 174 are configured to receivepackets from the switch fabric 174 and to send the packets to thecontrol processor 162 (or more specifically, the ndOS executing on thecontrol processor) and/or to an NPU (172A, 172B). Further, the internalports are configured to receive packets from the control processor 162(or more specifically, the ndOS executing on the control processor) andthe NPUs (172A, 172B).

In one embodiment, the control processor 162 is any processor configuredto execute the binary for the ndOS. In one embodiment, the NPU is aspecialized processor that includes functionality to processes packets.In one embodiment, the NPU may be implemented as any combination ofgeneral purpose hardware and/or special purpose hardware (e.g., FieldProgrammable Gate Arrays (FPGAs), Application Specific IntegratedCircuits (ASICs), etc.) and any type of storage and/or memory including,but not limited to, random access memory (RAM), dynamic random accessmemory (DRAM), static random access memory (SRAM), NAND-type flashmemory, NOR-type flash memory, any other type of memory, any other typeof storage, or any combination thereof. In one embodiment, the networkdevice (100) may also include Field Programmable Gate Arrays (FPGAs)and/or Application Specific Integrated Circuits (ASICs) that arespecifically programmed to process packets. In one embodiment, thenetwork device may include FPGAs and/or ASICs instead of NPUs. In oneembodiment, processing packets includes: (i) processing the packets inaccordance with layer 2, layer 3 and/or layer 4 protocols (where alllayers are defined in accordance with the OSI model), (ii) making a copyof the packet, (iii) analyzing (including decrypting and/or encrypting)the content of the header and/or payload in the packet, and/or (iv)modifying (including adding or removing) at least a portion of theheader and/or payload in the packet.

In one embodiment, the switch fabric 180 is configured to: (i) sendpackets received from the internal ports 174 to the appropriate externalports 176 and (ii) send packets received from the external ports 176 tothe appropriate internal ports 174.

In one embodiment, the switch fabric classifier 178 is configured toapply a classification rule to each packet received by the switch fabricto determine: (i) whether to send the received packet to an externalport, (ii) whether to send the received packet to an internal port,and/or (iii) whether to send the received packet to the PCIe switch 170.

In one embodiment, the classification rule includes a classificationcriteria and an action. In one embodiment, the classification criteriaspecifies a media access control (MAC) address, an Internet Protocol(IP) address, a Transmission Control Protocol (TCP), user datagramprotocol (UDP), an OSI layer 4 information related to a TCP ports, anIPSec security association (SA), a virtual local area network (VLAN)tag, a 802.1Q VLAN tag, or a 802.1Q-in-Q VLAN tag, or any combinationthereof. In one embodiment, the action corresponds to an action to beperformed when a packet satisfying the classification rule isidentified. Examples of actions include, but are not limited to, (i)forward packet to the control processor (via a specific internal port orthe PCIe switch), (ii) forward packet to an NPU (via a specific internalport or the PCIe switch), and (iii) send a copy of the packet to aspecific external port, count the packet into one byte and packetcounter or into a plurality of such counters based on further criteriasuch as packet size, latency, metadata such as physical ports foringress or egress, etc., add meta data to any copied or forward packetsuch as timestamps, latency, physical ingress or egress path, etc.

In one embodiment, the switch fabric 180 is configured to communicatewith the control processor 162 and/or the NPUs 172A-172B using aPeripheral Component Interconnect Express (PCIe). Those skilled in theart will appreciate the other hardware based switchingframeworks/mechanisms may be used in place of (or in addition to) PCIe.

In one embodiment, the persistent memory 164 is configured to store thebinary for the ndOS. The persistent memory 164 may be implemented usingany non-transitory storage mechanism, e.g., magnetic storage, opticalstorage, solid state memory, etc.

In one embodiment, the volatile memory 166 is configured to temporarilystore packets in one or more queues 168. The volatile memory may beimplemented using any non-persistent memory, e.g., RAM, DRAM, etc. Inone embodiment, each of the queues is configured to only store packetsfor a specific flow. In one embodiment, a flow corresponds to a group ofpackets that all satisfy a given classification rule.

It is noted that the embodiments illustrated in FIG. 5 are exemplary.Other embodiments may utilize different communication interfaces(Ethernet, PCIe, PCI, etc.), network devices with less components oradditional components, arrange the components in a differentconfiguration, include additional interconnects or have fewerinterconnects, etc. The embodiments illustrated in FIG. 5 shouldtherefore not be interpreted to be exclusive or limiting, but ratherexemplary or illustrative.

FIG. 6 illustrates an exemplary embodiment of a network device orswitch. The exemplary ndOS switch 104 includes a plurality of Ethernetports (e.g., 48 1/10 Gb ports and 4 40 Gb ports), a high-speedinterconnect that connects the internal modules within the switch (e.g.,PCIe, Ethernet), and 2 CPU sockets for hosting 2 respective CPUs.

The ndOS switch 104 further includes a networking processing unit andRAM (e.g., 512 Gb), which may host the ndOS program while being executedby the one or more CPUs. The switch 104 further includes 2 drive baysfor internal non-volatile storage, and 2 external drive bays forexternal storage (e.g., hard disk drive (HDD) or solid state drive(SSD)). Additionally, the ndOS switch 104 includes one or more powersupplies, PCI slots (e.g., 4 PCI slots), and fans.

It is noted that the embodiment illustrated in FIG. 6 is exemplary.Other embodiments may utilize different components, have more or lessamount of any of the components, include additional components, or omitone or more components. The embodiment illustrated in FIG. 6 shouldtherefore not be interpreted to be exclusive or limiting, but ratherexemplary or illustrative.

FIG. 7 illustrates resource coherency and analytics engines inaccordance with one or more embodiments. The Resource Coherency andAnalytics engine (RCAE) 200 interacts with a switch fabric 202 inaccordance with one or more embodiments. The RCAE 200 includes ports(e.g., 204, 206, 208, 210) configured to receive packets from a network(e.g., a wide area network (WAN), a local area network (LAN), theInternet) or the switch fabric 202 and to provide the packets to theappropriate virtual traffic shaper (VTS) (e.g., 212, 214, 216, 218). Theports in the RCAE may also be used to transmit packets to a network orto the switch fabric. The switch fabric 202 is configured to receivepackets from and send packets to the RCAE via ports (e.g., 220, 222) inthe switch fabric.

Each VTS is configured to process the packets received from theaforementioned ports and, if appropriate, send the packets to anotherport in the RCAE. The VTS processes the packets based on operatingparameters set by the vCoherence Controller (VCC) 226. In oneembodiment, the operating parameters may be determined based on one ormore of the VRCLs.

The operating parameters may include, but are not limited to, virtualoutput queue (VOQ) length, drain rate of VOQ (referred to as “drainrate”), cut-through policies, and VOQ scheduling policies. In oneembodiment, the VOQ length corresponds to a maximum number of packetsthat may be queued in the VOQ at any one time. In one embodiment, thedrain rate corresponds to the rate at which packets queued in a givenVOQ are removed from the VOQ and scheduled for transmission. The drainrate may be measured as data units/unit time, e.g., megabits/second. Inone embodiment, cut-through policies correspond to policies used todetermine whether a given packet should be temporarily stored in a VOQor if the packet should be sent directly to a VOQ drainer. In oneembodiment, VOQ scheduling policies correspond to policies used todetermine the order in which VOQs in a given VTS are processed.

The VCC 226 obtains RCAE statistics from the vResource Snooper (VRS) 224and uses the RCAE statistics to update and/or modify, as necessary, theoperating parameters for one or more VTSs in the RCAE. In oneembodiment, the VCC 226 may obtain RCAE statistics directly from theindividual VTSs. Those skilled in the art will appreciate that othermechanisms may be used to obtain the RCAE statistics from the VTS by theVCC without departing from the embodiments.

In some embodiments, the VCC 226 includes functionality to obtain RCAEstatistics from all VRSs 224 in the RCAE and then to change the drainrates (described below) for one or more VOQ drainers based on the RCAEstatistics obtained from all (or a portion) of the VTSs. The VCC 226 mayalso provide particular RCAE statistics to the VTS or components withinthe VTS, e.g., the VRCL enqueuer and VOQ Drainer, in order for the VTS(or components therein) to perform their functions.

The RVS 224 is configured to obtain RCAE statistics from the individualVTSs. The RCAE statistics may include, but are not limited to, (i)packets received by VTS, (ii) packets dropped by VRG classifier, (iii)packets dropped by the VRCL enqueuer, (iv) packets queued by each VOQ inthe VTS, (v) number of cut-through packets, (vi) queue length of eachVOQ in the VTS, (vi) number of packets scheduled for transmission by VOQdrainer, and (vii) latency of VTS. The RCAE statistics may be sent tothe VRS 224 as they are obtained or may be sent to the VRS 224 atvarious intervals. Further, the RCAE statistics may be aggregated and/orcompressed within the VTS prior to being sent to the VRS 224.

In one embodiment, updates or modifications to the operating parametersof the one or more VTSs are sent to the vResource Policy Feedback Module(RPFM) 228. The RPFM 228 communicates the updates and/or modificationsof the operating parameters to the appropriate VTSs. Upon receipt, theVTSs implement the updated and/or modified operating parameters. Inanother embodiment, any updates or modifications to the operatingparameters of the one or more VTSs are sent directly to the VTSs fromthe VCC.

FIG. 8 is a flowchart of an algorithm for processing packets received bya VTS in accordance with one or more embodiments. While the variousoperations in this flowchart are presented and described sequentially,one of ordinary skill will appreciate that some or all of the operationsmay be executed in a different order, be combined or omitted, or beexecuted in parallel.

In operation 800, a packet is received at an input port for the networkdevice. The packet is then forwarded to the appropriate packet processor(PP) VTS. In operation 802, the header information and/or meta-packetdata is obtained from the packet. In one embodiment, operation 802 isperformed by a VRG classifier.

In operation 804, the VRG associated with the packet is determined usingthe header information obtained in operation 802. In one embodiment,operation 802 is performed by a VRG classifier. In operation 806, theegress physical port (EPP) is determined using the header information.In one embodiment, operation 806 is performed by a VRG classifier.

In operation 808, a determination is made about whether the packet isassociated with a rule. In one embodiment, a look-up is performed usingthe VRG-EPP information obtained in the prior operations. If there is ahit for the VRG-EPP pair—namely, a corresponding entry in datastructure, then the process proceeds to operation 812. Alternatively, ifthere is no hit then the process proceeds to operation 810.

In operation 810, a default action is performed. The process thenproceeds to operation 816. In operation 812, the rule-specific action(s)associated with the rule are obtained. In operation 814, the rulespecific actions are performed. The process then proceeds to operation816. In operation 816, a determination is made about whether a triggercondition exists. If a trigger condition exists, then the processproceeds to operation 818; otherwise the process ends. In operation 818,an appropriate configuration action is performed. In one embodiment, theconfiguration performed in operation 818 corresponds to a micro-levelpolicy.

FIGS. 9A-9H illustrate sample embodiments of a switch module coupled toone or more servers and a switch controller. As previously describedwith reference to FIG. 1A, a data center rack often includes servers anda top-of-the rack (TOR) switch to connect the rack devices to a network.Of course, although TOR switches are used for description purposes, theprinciples presented herein may be applied to switches situated in anyposition on the rack.

Embodiments provide for devices that combine server functions withswitching capabilities. This way, one device in the rack can act as adual purpose device providing server functionality and networkcapabilities. However, these multi-function devices may also beinstalled in racks with a separate ndOS switch (e.g., see FIG. 9B).

For description purposes, a device with multiple servers and switchingcapabilities is referred to herein as a “multi-server with switching”device. Additionally, when the functionality of a single server iscombined with switching functionality, the resultant device is referredto as a “single-server with switching” device. Further, a “switchingserver” or a “networking device system” is used for description purposesto describe the functionality of either a multi-server with switching ora single-server with switching.

Some embodiments include ndOS inside the switching server, which meansthat the functionality of ndOS may be expanded to components inside theswitching server, which allows further control of the layer 2 fabric byimplementing networking policy on packets even before the packets leavethe switching server.

FIG. 9A is a multi-server with switching ndOS device 902 that includes 4servers 904, a switch module 916 (e.g., an integrated circuit), and aswitch controller 922 (e.g., a switch controller card coupled to a PCIeport), according to one embodiment.

Switch module 916 includes switch fabric 918, a plurality of PCIe ports914 and 920, and a plurality of Ethernet ports 924. Each of the serversincludes a PCIe port 912 and the servers are coupled to the switchfabric 916 via the PCIe connections. In addition, a switch controller922 is also coupled to the switch module 916 via PCIe port 926. In oneembodiment, switch module 916 is an integrated circuit, and in otherembodiments, switch module 916 may include a plurality of componentsthat interact to provide the functionality described herein.

In one embodiment, switch module 916 provides networking capabilitiesfor the servers. However, the servers do not include a network interfacecard (NIC), but the servers communicate via PCIe connections to theswitch module that provides networking capabilities for the servers.Therefore, the switch module 916 acts as a NIC for the four servers. Inone embodiment, the four servers share other resources, such as a powersupply.

To provide networking capability at the servers (e.g., Ethernetnetworking), a network driver 908 is installed in the operating systemexecuting at each of the servers. The network driver 908 provides avirtual network interface card (VNIC) for the applications executing onthe servers. Therefore, applications running in the servers will accessthe VNIC 906 to access the network. In other words, although server 1904 does not include an Ethernet VNIC, server 1 904 provides theEthernet NIC capabilities via software driver 908. Ethernet packets aretransferred through the PCIe connection (e.g., PCIe 912 to PCIe 914) andout to the network via Ethernet ports 924.

In one embodiment, the network driver 908 includes ndOS capabilities.Because ndOS is a distributed network operating system, all or some ofthe features mentioned above for ndOS may be implemented at the networkdriver 908 inside the server. For example, a network administrator mayconfigure the ndOS 910 to not switch any packets at the network driver908, not even those packets that originate at server 1 and are addressedfor server 1, and send those packets to the switch module 916 soanalytics may be performed on these packages (e.g., monitor the flow ofpackets through the layer 2 fabric).

Because the servers are separate from the networking functions providedby the switch module 916, users can upgrade the servers (e.g., add newprocessors, or replace the server card altogether) without having toupgrade the networking devices.

Managing the networking for the multi-server unit is a difficult tasksince the four servers are sharing networking. However, because of theflexibility of ndOS and its ability to automatically configure the layer2 fabric, it is possible to manage the networking features for themulti-server unit easily.

The switch controller 922 includes, besides the PCIe port 926 mentionedabove, a CPU, a network processing unit 928, RAM, and non-volatilestorage 934. Switch controller 922 includes a program that implementsthe ndOS 930, including the coherence and analytics modules 932associated with the ndOS, when executed by the processor.

In one embodiment, switch module 916, together with switch controller922, provide similar functionality to the ndOS switch describedhereinabove (e.g., FIGS. 5-7). But the combination also provides thePCIe interface used to provide networking services to the servers insidethe multi-server with switching device 902.

In one embodiment, a networking device system 902 includes a switchmodule 916, a plurality of servers 904, and switch controller 922. Theswitch module includes one or more ports with a communications interfaceof a first type (CI1) (e.g., PCIe, although other communicationinterfaces are also possible) and one or more ports with acommunications interface of a second type (CI2) (e.g., Ethernet,although other communication interfaces are also possible).

The plurality of servers is in communication with the switch module viafirst CI2 couplings, the servers including a respective virtual CI1driver that provides a CI1 interface to applications in the respectiveserver. Each virtual CI1 driver is defined to exchange CI1 packets withthe switch module via the first CI2 coupling, and each virtual CI1driver also includes a first network device operating system (ndOS)program.

The switch controller is in communication with the switch module via asecond CI2 coupling, the switch controller including a second ndOSprogram that, when executed by a processor, controls packet switchingpolicy in the switch module. The packet switching policy, also referredto herein as the networking policy or global switching policy, includesa definition for switching incoming packets through the switch module orthrough the switch controller. The first ndOS programs and the secondndOS program, when executed by respective processors, exchange controlmessages to maintain the network policy for the layer 2 switch fabric.

In another embodiment, the switch module further includes a classifier,the classifier implementing the packet switching policy for incomingpackets. The second ndOS is defined to configure the classifier toimplement the packet switching policy.

In just another embodiment, the first ndOS and the second ndOS aredefined to interact with other ndOS programs in layer 2 switch fabric.Further, packets switched by the switch controller are sent from theswitch module to the memory in the switch controller.

In yet another embodiment, the switch controller further includes apacket processor. In addition, the switch module further includes aswitch fabric defined to switch packets between ports.

It is noted that the embodiments illustrated in FIG. 9A are exemplary.Other embodiments may utilize different number of servers, differentswitch modules, different switch controller's, etc. The embodimentsillustrated in FIG. 9A should therefore not be interpreted to beexclusive or limiting, but rather exemplary or illustrative.

FIG. 9B is a multi-server with switching ndOS device 902 coupled to aTOR switch 936 via Ethernet ports, according to one embodiment. The TORswitch 936 includes a switch fabric 938, Ethernet ports 942, NPU 940, aprocessor, RAM, non-volatile storage 944, and an ndOS module 946 (e.g.,program) that includes a coherence-and-analytics engine 948.

Because ndOS is a distributed network operating system and is present inthe server network driver 908, in the switch controller 922 (whichmanages the switch module 916), and in TOR 936, it is possible toimplement a packet switching policy (i.e., a layer 2 fabric policy) thatis centrally managed and implemented across the network. The packetswitching policy or network policy includes the rules and configurationsdefined for managing resources on the network, such as:

-   -   managing resources across the switch fabric, managing flows and        service levels, managing bandwidth, creation/management of VRGs,        creation/management of access control lists (ACL) and VRCLs,        performing analytics on flows passing through network devices,    -   defining how packets are switched in the ndOS switch (e.g.,        through the switch fabric, the packet processor, or the        processor in the switch controller), maintaining policies for        MAC address management at the switch (see more details below        with reference to FIGS. 12A-12B and 13), delivering defined        SLAs,    -   supporting policies and protocols for exchanging information        among ndOS devices, exchanging topology information among ndOS        devices, creation and modification of configuration parameters        on network devices, notification of changes in the layer 2        fabric, discovery of ndOS switches,    -   creation and management of virtual networks, isolation of        traffic from virtual networks, tagging of packets, support for        SLAs in each virtual network,    -   creation of virtual machines (VM) on the switch, creating of VMs        on hosts, migrating VMs from one host to another host,        interfacing with hypervisors on hosts, providing boot images for        hosts (see more details below with reference to FIGS. 11A-11B),        etc.

As previously discussed with reference to FIGS. 1A-1B, the ndOS modulesdistributed across the layer 2 fabric are able to exchange informationto implement a layer 2 fabric that appears, from the managementperspective, as one big switch that includes all the switching deviceshaving ndOS. Therefore, the ndOS modules 910, 930, and 946 exchangeinformation to implement the global switching policy.

In one embodiment, the ndOS module 910 inside each server is managed bythe ndOS module 930 in the switch controller. This way, theimplementation of the ndOS module 910 in the servers can be simplified,leaving some of the ndOS features to be supported by the ndOS module 930in the switch controller.

FIG. 9C is a multi-server with switching ndOS device 952 with threeservers and virtual Ethernet VNICs 906 inside each server, according toone embodiment. In the embodiment of FIG. 9C the network driver 908 doesnot include an ndOS module. In this case, the network driver 908provides a virtual Ethernet NIC for Server 1. From the point of view ofthe operating system executed in server 1, the Ethernet driver 906behaves exactly as a hardware NIC. The VNIC 906 receives Ethernetpackets from the operating system or the applications in server 954, andtransmits those packets to the switch module 914 via the PCIe connectionbetween server and switch module 916. Respected VNIC Ethernet drivers inthe other servers also provide the Ethernet VNIC functionality.

In one embodiment, the network driver 908 may create a plurality ofVNICs (not shown), each VNIC appearing to the operating system as onephysical hardware NIC. For example, in one embodiment, network driver908 can create up to 255 VNICs. Of course, each of the VNICs will routeits Ethernet traffic through the PCIe port to the switch module 914.

Since the network driver 908 receives Ethernet packets and sends themthrough the PCIe connection, the network driver 908 performs aconversion or an encapsulation of the packets to transmit them throughthe PCIe port. In one embodiment, the Ethernet packets are encapsulatedand transmitted through the PCIe connection, and the switch module 914de-encapsulates the Ethernet packets before sending them through itsEthernet ports.

The network driver includes buffer and DMA management to provide therequired lossless behavior on the PCIe port and channel with therequired polling or interrupt based notification, and the buffer andEthernet format header and CRC on the Ethernet ports and the ability toconvert as needed. In additional fragmented packets are reconstructed asneeded before transmission on PCIe, and larger PCIe packets arefragmented as required by the Ethernet port max packet size.

It is noted that the embodiments illustrated in FIG. 9C are exemplary.Other embodiments may utilize different number of servers, support othercommunication interfaces, etc. The embodiments illustrated in FIG. 9Cshould therefore not be interpreted to be exclusive or limiting, butrather exemplary or illustrative.

FIG. 9D shows the multi-server with switching 952 of FIG. 9C coupled toa TOR switch 936, according to one embodiment. In this embodiment, thendOS is present in the switch controller and in the TOR switch 936. ThendOS functionality is therefore present in the multi-server 952 and inthe external switch.

In one embodiment, although the network driver 908 does not have ndOScapabilities, the ndOS module 930 in switch controller 922 interactswith the network driver 908 to manage the network traffic flowingthrough network driver 908. For example, the ndOS module 130 may commandthe network driver 908 to reduce the flow of traffic flowing into thenetwork in the presence of network congestion. This means that, althoughnetwork driver 908 does not implement ndOS, network driver 908 can stillassist ndOS module 930 in the switch controller to implement ndOSpolicies.

In another embodiment, the ndOS module 930 is able to act as anarbitrator between the traffic generated by all the servers inmulti-server unit 952. The ndOS module 930 may implement networkpolicies (e.g., bandwidth control) at the server level, instead ofhaving to manage the policies at the multi-server level. For example, ifthe ndOS 930 detects that one of the servers is producing a large amountof traffic, causing network congestion on the other servers, ndOS 930 isable to exchange control messages with the network driver 908 todecrease the flow of packages (e.g., reduce the bandwidth allocated tothe VNIC) coming from the server monopolizing network traffic on themulti-server unit.

Once the congestion disappears, the ndOS 930 may command the Ethernetdriver in the corresponding server to restore the original bandwidthallocated to the VNIC.

In another embodiment, the ndOS 930 may also establish use policiesamong the different servers, even if the absence of network congestion.For example, if the network administrator allocates 30 Gb of traffic tothe multi-server 952, the ndOS may configure each of the network drivers908 to a maximum of 10 Gb. However, the assignment on bandwidth does nothave to be symmetrical. For example, if one of the servers is a webserver expecting to generate a large amount of traffic from users, thendOS 930 may allocate 20 Gb to this server, and 5 Gb to the other twoservers.

FIG. 9E is a single-server with switching 962, according to oneembodiment. In the embodiment of FIG. 9B, the switching server 962includes server 964, switch module 916, and switch controller 922. Inthis exemplary embodiment, the switch controller is also coupled to theserver via a PCIe connection. (It is noted that the direct communicationbetween switch controller and server is also present in some embodimentsfor the devices of FIGS. 9A-9D). Therefore, the switch controller 922may communicate directly with ndOS 910 to implement network policies. Inother embodiments, the switching server does not include a directconnection between server 964 and switch controller 922.

In one embodiment, NdOS 910 has all the features of an ndOS device.Therefore, ndOS 910 is able to implement network policies regardingtraffic and service levels at the server level. For example, if server964 includes a plurality of virtual machines, ndOS 910 may implementresource allocation (e.g., bandwidth assignments) among the differentvirtual machines. In addition, ndOS 910 is able to implement virtual LANfunctionality and keep separate the traffic for VMs in different VLANs(e.g., the VMs in the different virtual networks described in FIG. 3).

In one embodiment, the switch module 916 includes a classifier (notshown) and ndOS 930 configures the classifier in switch module 916 todetermine how packets are switched. In one embodiment, the networkpackets may be switched through the switch fabric, through the NPU inswitch controller 922, or through the processor in the switch controller922. The classifier determines how each packet is routed according tothe rules programmed into the classifier.

In one embodiment, a networking device system includes a switch module,a server, and the switch controller. The switch module has one or moreports with a communications interface of a first type (CI1) and one ormore ports with a communications interface of a second type (CI2).Further, the server is in communication with the switch module via afirst CI2 coupling, the server including a virtual CI1 driver thatprovides a CI1 interface to applications in the server. The virtual CI1driver is defined to exchange CI1 packets with the switch module via thefirst CI2 coupling, and the virtual CI1 driver further includes a firstnetwork device operating system (ndOS) program.

The switch controller is in communication with the switch module via asecond CI2 coupling, and the switch controller includes a second ndOSprogram that, when executed by a processor, controls packet switchingpolicy in the switch module. The packet switching policy includes adefinition for switching incoming packets through the switch module orthrough the switch controller, where the first ndOS program and thesecond ndOS program, when executed by respective processors, exchangecontrol messages to maintain a network policy for a layer 2 switchfabric.

In one embodiment, the switch module further includes a classifier, theclassifier implementing the packet switching policy for incomingpackets, where the second ndOS is defined to configure the classifier toimplement the packet switching policy. Further, in another embodiment,the first ndOS and the second ndOS are defined to exchange controlmessages with other ndOS programs in the layer 2 switch fabric tomaintain the network policy for the layer 2 switch fabric.

In one embodiment, the packets switched by the switch controller aresent from the switch module to memory in the switch controller. Inanother embodiment, the switch controller further includes a packetprocessor.

In yet another embodiment, the overall layer 2 switching strategyfurther includes managing one or more of migration of virtual machinesfrom one host to another host, access control lists (ACL) for networkentities, analytics on flows passing through at least one networkdevice, creation of virtual machines, creation of virtual machines on ahost device coupled to the switch, changing configuration parameters onnetwork devices, notification of changes in the layer 2 fabric,bandwidth management, tagging, virtual networks, of quality of serviceimplementation.

In one embodiment, CI1 is Ethernet and CI2 is Peripheral ComponentInterconnect Express (PCIe). In another embodiment, the switchcontroller includes non-volatile read/write storage.

FIG. 9F illustrates the single-server with switching 962 of FIG. 9Ecoupled to a TOR switch 936, according to one embodiment. As describedabove, different ndOS modules in the network driver at the server 964,the switch controller, and the TOR switch 936, interact implement theglobal network policies, such as controlling the flows in bandwidthutilized by different applications (e.g., VMs) in the server.

FIG. 9G is a single-server with switching 962 with a virtual EthernetVNICs, according to one embodiment. In one embodiment, although thenetwork driver 908 does not have ndOS capabilities, the ndOS module 930in the switch controller interacts with the network driver to manage thenetwork traffic flowing through network driver 908. For example, thendOS module 130 may command the network driver 908 to reduce the flow oftraffic flowing into the network in the presence of network congestion.

In another embodiment, the ndOS module 130 is able to act as anarbitrator between the traffic flows generated within the server. ThendOS module 130 may implement network policies (e.g., bandwidth control)at the server level, instead of having to manage the policies at theswitch level. For example, if the ndOS 930 detects that one VM in theserver is producing a large amount of traffic, causing networkcongestion on the network driver, ndOS 930 is able to exchange controlmessages with the network driver 908 to decrease the flow of packagesfor that VM (or for the virtual network where the VM is communicating).

Once the congestion disappears, the ndOS 930 may command the Ethernetdriver in the corresponding server to restore the original bandwidthallocated to the previously restricted VM.

FIG. 9H illustrates the single-server with switching of FIG. 9G coupledto a TOR switch, according to one embodiment. In one embodiment, theimplementation of virtual networks may be done at the switch, and theserver does not have to perform virtual network related operations. Forexample, the tagging or encapsulation of VXLAN headers may be done atthe switch. In another embodiment, the tagging or encapsulation of VXLANheaders may be done at the network driver. In addition, the networkdriver at the server can be configured to perform the VXLANencapsulation for one VNIC or for some of the VNICs created by thenetwork driver.

This flexibility facilitates the implementation of SLAs by ndOS becausethe server does not need to be aware of the network restrictions,leaving the complexity of managing flows, isolations, resources, etc.,to the distributed ndOS.

The management of the ndOS devices may be distributed. For example inone embodiment, the administrator or the network management software,interact with the TOR switch, which in turn interfaces with the ndOS inthe switch controller and/or the network driver in the server, or withthe ndOS in the network driver.

For example, the network policy may define that the switch in theswitching server does not switch packets locally, and to send everypacket to the TOR switch. This way, the TOR switch may enforce thenetwork policies defined by the ndOS (e.g., EGS configuration, LLDPconfiguration, forced frame, tagging, MAC address assignment, linkaggregation, etc.).

It is noted that the embodiments illustrated in FIGS. 9A-9H areexemplary. Other embodiments may utilize different configurations of theelements presented, omit some component, add new component, provideredundancy with duplicated components, spread the functionality of onecomponent among a plurality of components, etc. The embodimentsillustrated in FIGS. 9A-9H should therefore not be interpreted to beexclusive or limiting, but rather exemplary or illustrative.

FIGS. 10A-10B illustrate a networking software architecture in a server,according to one or more embodiments. In FIG. 10A, server 904 includesan operating system 302 which provides a network interface 306, alsoreferred to as network API, for the applications 304 running on theoperating system 302. The networking provided by the operating systemincludes a network stack including networking protocols such as TCP,UDP, IP, etc.

The ndOS driver 908 provides a VNIC to the operating system, that fromthe point of view of the operating system behaves exactly like ahardware NIC. The network packets are transmitted to the switch module960 via that the PCIe connection, as described above.

FIG. 10B includes a ndOS driver that provides a plurality of VNICs 322,324, and 326, where each VNIC provides the same functionality of ahardware network card NIC. Each PCIe port in the server is able to actas an Ethernet NIC that can support a plurality of virtual EthernetNICs.

In one embodiment, the management is done by the ndOS, either by themodule in the switch module 916 or in the TOR switch. The ndOS is ableto allocate the bandwidth among the different apps, virtual NICs,virtual networks, etc. additionally, the ndOS is able to provide thedifferent services described above regarding networking policy, such asencapsulation, tagging, tunneling, QOS, traffic queues management,packet redirection, etc.

FIGS. 11A-11B illustrate the interactions between a hypervisor and thendOS, according to one or more embodiments. In one embodiment, theoperating system 302 in the switching server executes a hypervisor 852that provides a virtual environment for a plurality of VMs 854. Becausehypervisor 852 provides virtual network environments, the hypervisor 852is able to create virtual NICs 858 (referred to as HVNICs in FIG. 11A)for the VMs 854.

In the exemplary embodiment of FIG. 11A, hypervisor 852 has createdthree HVNICs and the ndOS driver has created two VNICs 860. In oneembodiment, the hypervisor is not aware that the NICs provided by theoperating system 302 are virtual NICS. As a result, the hypervisorroutes the traffic for the HVNICs through the VNICs created by the ndOSdriver.

In another embodiment (not shown), the ndOS driver is able to interfacewith hypervisor 852 and the ndOS driver creates the virtual NICsnecessary for the hypervisor. This way the hypervisor does not have todeal with the complexity of supporting virtual NICs. Further, since thendOS driver implements the ndOS across a plurality of devices, theservices provided by ndOS are better implemented by the ndOS-awaredevices, which results in the use optimization of network resources.

The hypervisor may want to perform an operation that requires networkaccess, such as getting a Dynamic Host Configuration Protocol (DHCP)address, sending an Address Resolution Protocol (ARP) request, getting aboot image, installing a program, installing a driver, installing anupgrade, etc. In one embodiment, the ndOS is able to intercept thesenetwork requests and satisfy them directly, without having to go to adifferent server for the requested information or data.

In one embodiment, the ndOS is aware of the hypervisors in the network,or ndOS is defined to detect hypervisor-related operations. NdOS is ableto identify any type of network packet and configure actions to beperformed in response to, or based on, those packets.

For example, the ndOS may intercept a Preboot eXecution Environment(PXE) boot request, or some other network request (e.g., a DCHP request,an ARP request, a RARP request, a DNS request, a multicast that containsa VXLAN ARP, etc.) and satisfy the request from the switch controller inthe network server or from the TOR switch. In other words, the ndOS mayact as a meta-hypervisor for the individual hypervisor's in the server.For example, the ndOS module may start, reboot, or shut down thehypervisor, migrate VMs, etc. In one embodiment, the ndOS switch mayalso act as a server and respond to a request for a boot image server,or for some other network you request. For example, the ndOS switch mayrespond to a PXE redirection service request on the network (Proxy DHCP)and give its own address as an available PXE boot server.

Oftentimes, hypervisors attach to discs through logical unit devices(LUNs), and when booting up, the hypervisors will obtain the publicimage from one of the storage devices. In one embodiment, one or morendOS modules are defined to store the images in their permanent (i.e.,non-volatile) storage 408. When a hypervisor sends a request for a bootimage, the ndOS intercepts the request and serves the boot image fromstorage, instead of having to go to the network to download the bootimage.

This scenario is particularly helpful when there is a power failure inthe data center. After the power is restored, a plurality of hypervisorsor servers may be booting up at the same time (e.g., thousands ofservers), creating a large amount of traffic on the network andcongestion at the servers that provide the boot images. By having thendOS modules provide the boot images, the booting time is greatlyreduced and network traffic is also significantly reduced.

Additionally, the ndOS may also restart hypervisors at any time byproviding the boot image, maybe even reboot a server with a differenthypervisor and a different boot image.

FIG. 11B illustrates a sample architecture that includes boot imagespermanently stores in the TOR switch, according to one embodiment. Asdescribed above with reference to FIG. 11A, the boot image for startinga hypervisor is stored in the permanent storage or in the switchcontroller. In FIG. 11B, the boot images are stored in the permanentstorage 870 of the TOR switch. As described above, the TOR switch isable to intercept requests sent over the network, such as a boot imagerequest, and serve those requests from the ndOS in the TOR switch.

In one embodiment, a hierarchical model is used to determine where themaster copy of a boot image is kept. For example, the master boot imagesmay be stored on a master server, and the ndOS instances request ordownload their boot images from the master server. Additionally, an ndOSmodule may download the boot image from another ndOS module. In oneembodiment, the system operates similar to a caching operation inmemory, where different level of caches, which would correspond todifferent levels in the hierarchy for storing boot images in the ndOSmodules. This provides flexibility in the implementation of complex datacenter environments with a plurality of different types of servers(e.g., Linux, Windows, VMWare, Openstack, etc.).

Additionally, FIG. 11B illustrates how the different ndOS modulesinteract with each other, with the operating system, or with thehypervisor. This flexibility enables an easy-to-manage data centerenvironment.

FIGS. 12A-12B illustrate a multilevel distributed MAC tablearchitecture, according to one or more embodiments. As discussed above,incoming packets may be routed through the switch fabric, the packetprocessor, or the processor. In one embodiment, each of these componentskeep its own MAC address table, which holds information regardingswitching packets based on their MAC address.

However, the sizes of the tables may vary considerably, as the amount ofresources available for storage varies. For example, the switch fabricmay perform fast switching operations utilizing CAMs or TCAMs 606, butthese content addressable memories typically have a limited amount ofcapacity. The packet processor usually has a larger amount of memory andalso keeps a MAC address table 602, and the packet processor keeps, inone embodiment, its MAC address table in RAM memory, which can have asize of gigabytes, allowing for a large number of entries in theprocessor MAC table 166.

A Content-Addressable Memory (CAM), also known as associative memory,associative storage, or associative array, is a type of computer memorywhere a computer program supplies a data word and the CAM searches itsentire memory to see if that data word is stored anywhere therein. Ifthe data word is found, the CAM returns a list of one or more storageaddresses where the word was found, and in some architectures, it alsoreturns the data word, or other data associated with the request. ATernary CAM (TCAM) is a type of CAM that allows the use of “wildcards,”a third matching state of “X” or “Don't Care,” for one or more bits inthe provided data word, thus adding flexibility to the search by usingBoolean logic.

In one embodiment, a switching goal is to have packets switched as fastas possible, and having the hardware (e.g., the switch fabric) switch amajority of the packets. However, the tradeoff for having high speed isto use expensive CAM or TCAM tables having limited sizes. Typically, theTCAMs have a small size (e.g., 128K). However, in environments withvirtual machines, there can be millions of MAC addresses on the network.In one embodiment, the ndOS programs the switch fabric so if there is aMAC address miss, the switch fabric lets ndOS determine how to switchthe packet.

When a packet comes in with a MAC address absent from the switch-fabricMAC 606, the switch fabric must send the packet to the packet processor(e.g., NPU) or to the processor. In addition, a packet with the MACaddress in MAC table 606, may also be forwarded to the packet processoror the processor according to classification rules. In one embodiment,there are three MAC tables in the ndOS switch, with three differentsizes and different levels of performance.

In one embodiment, control processor 162 will take an action after amiss in the MAC table 606 (or any other MAC table), such as adding theMAC address of the miss to one of the MAC tables 606, 604, or 602. If aMAC address for a received packet is not in any of the MAC tables, thecontrol processor 162 may initiate a discovery process to find thedestination switch, or the egress port in the switch, for that address.In one embodiment, the ndOS system can switch the packet that caused theMAC address miss in one or more of the MAC tables, without making anyupdates to the MAC tables (e.g., the packet caused a miss in the switchfabric MAC table 606 but it was a hit in MAC table 602 of the NPU).

It is noted that, in one embodiment, the MAC tables are independent andupdates to each of the tables may be performed independently. In anotherembodiment, the control processor utilizes logic to manage the contentof the MAC tables, acting as a multilevel memory with different cachingoptions for storing MAC address information.

In addition, control processor 162 may utilize heuristic algorithms tomanage the content of the different MAC tables. For example, a newaddress may be added to MAC table 606 after performing an operation toremove one of the current entries in the table. The control processormay utilize any method to clear entries, such as least recently used(LRU), less frequency of use, FIFO, etc.

In one embodiment, the same principles presented herein with referenceto MAC tables, may be applied to other data structures in the switch,such as IP tables, routing tables, VM tables, virtual network tables,etc.

FIG. 12B includes a switch fabric with two levels of MAC tables,according to one embodiment. In the exemplary embodiment of FIG. 12B,the switch fabric includes two levels of MAC tables, a TCAM MAC table608, and a RAM MAC table 606. In one embodiment, the switch fabricincludes logic for keeping addresses in the TCAM table or in regularnon-volatile memory. In general, MAC addresses associated with heavynetwork traffic will be in the TCAM table, while other addresses arekept in the MAC table 606.

Of course, the ndOS is able to manage the two levels of MAC tables atthe switch fabric, together with the MAC tables in the NPU and volatilememory associated with the controller, as discussed above with referenceto FIG. 12A, except that another level of MAC address storage is added.

Further, the concept of multilevel MAC table management may be expandedto the level 2 fabric, with the ndOS managing the content of the MACaddress tables across a plurality of ndOS switches. For example, aglobal MAC address table encompassing a plurality of devices may bepartitioned, replicated, etc., across the plurality of devices.

It is noted that the embodiments illustrated in FIGS. 12A-12B areexemplary. Other embodiments may utilize different levels of MAC tables,omit one of the MAC tables, omit some of the elements (e.g., oneembodiment may not include an NPU), etc. The embodiments illustrated inFIGS. 12A-12B should therefore not be interpreted to be exclusive orlimiting, but rather exemplary or illustrative.

FIG. 13 is a flowchart of a method for managing a distributed MAC table,according to one or more embodiments. While the various operations inthis flowchart are presented and described sequentially, one of ordinaryskill will appreciate that some or all of the operations may be executedin a different order, be combined or omitted, or be executed inparallel.

In operation 1002, a packet is received in one of the ports of theswitch (e.g., the switch fabric). From operation 1002, the method flowsto operation 1004 where a check is made to determine if the MAC addressof the packet is in the TMAC address table of the switch. If the addressis in the switch fabric MAC table, the method flows to operation 1014and otherwise the method flows to operation 1006.

In operation 1006, a check is made to determine if the MAC address is inthe RAM MAC table of the switch fabric. If a match is made (i.e., a hit)the method flows to operation 1014 and to operation 1008 otherwise. Inoperation 1008, the packet is sent to the NPU. From operation 1008, themethod flows to operation 1010, where a check is made to determine ifthe MAC address of the packet is in the NPU MAC table. If the address isin the NPU MAC table, the method flows to operation 1014 and tooperation 1012 otherwise.

In operation 1012, the packet is sent to the control processor and themethod continues to operation 1024, where a check is made to determineif the address is in the MAC table kept in memory by the controlprocessor. If the address is in the control processor MAC table, themethod flows to operation 1014 and to operation 1026 otherwise.

In operation 1026, the control processes determines what to do with theunknown address. For example, the control processor may take notice ofthe incoming port for the packet and add the MAC address to one or moreof the MAC tables. Additionally, the control processor may initiate adiscovery process to determine switching information for this address.

From operation 1026, the method flows to operation 1028, where a checkis made to determine if there is enough information to forward thepacket through the layer 2 fabric. If there is switching information forthe packet, the method flows to operation 1014 and to operation 1030otherwise. In operation 1030, the packet is dropped. An alternative todropping for operation 1030 could be to query some externally maintainedMAC table or utilize some other MAC address discovery method and use theresulting returned information to add the MAC table information to theLayer 2 Fabric.

As discussed above, there are multiple paths for the flow to reachoperation 1014, meaning that the switch has found a way to switch theincoming packet. In operation 1014, the packet is sent to itsdestination egress port. From operation 1014, the method flows tooperation 1016 were analytics for this package are performed by the ndOS(this operation is optional).

In operation 1018, a check is made to determine if any of the MAC tablesneed to be updated. If no table has to be updated, the method ends 1020.If one or more tables are to be updated, the necessary MAC tables areupdated in operation 1022.

FIG. 14 is a data structure for a MAC table, according to one or moreembodiments. In one embodiment, the MAC table in the control processorincludes one or more of the following fields:

-   -   The MAC address,    -   A VLAN identifier,    -   A VXLAN tag (which provides another level of virtual LAN        encapsulation),    -   Type of entry (dynamic or static),    -   Egress Port identifier for this MAC address,    -   Age of the entry,    -   Timestamp for the entry creation time,    -   Frequency of use for this MAC address,    -   Timestamp when this address was last used,    -   Flag indicating if an entry associated with this MAC address is        present in the TCAM of the switch fabric,    -   Flag indicating if an entry associated with this MAC address is        present in a first NPU in the switch,    -   Flag indicating if an entry associated with this MAC address is        present in a second NPU in the switch,    -   etc.

In one embodiment, the MAC tables in the switch fabric or the NPU have asimilar structure, but some of the fields may be omitted, or additionalfields may be added.

It is noted that the embodiment illustrated in FIG. 14 is exemplary.Other embodiments may utilize different fields, organize the fields in adifferent order, including fewer fields, etc. The embodimentsillustrated in FIG. 14 should therefore not be interpreted to beexclusive or limiting, but rather exemplary or illustrative.

FIG. 15 is a simplified schematic diagram of a computer system forimplementing embodiments described herein. FIG. 15 is an exemplaryhierarchy of switches, where a plurality of servers 706 are connectedvia TOR leaf switches D, E, F, G, H in respective data center racks 704.The leaf switches, also referred to as TOR switches, are connected tospine switches A, B, C, which are connected to router 702. It is notedthat multiple paths in the connections are included for redundancy andmultiple uplinks in one or more of the switches, but redundantconnections are not required to implement embodiments presented herein.

FIGS. 16A-16D illustrate exemplary embodiments of a distributed ndOS,according to one or more embodiments. Referring to the switches of FIG.15, it is possible to create a virtual network with limited bandwidththat is enforced at each local point within the hierarchy of switches.

FIG. 16A shows a virtual network spanning multiple leaf and spineswitches. For simplicity of description, it is assumed that there is nocontention with the leaf switches (B, C, and D), and that virtualmachines on switch B 720 b are trying to send 20 Gbps of sustainedbandwidth to virtual machines on a host connected to switch C 720 c. Atthe same time, virtual machines on hosts connected to Switch D 720 d arealso trying to send a sustained bandwidth of 40 Gbps to the same hostsconnected to switch C 720 c, and all these virtual machines belong to avirtual network which has been assigned a bandwidth limit of 20 Gbps.Assuming that all links have 10 Gbps bandwidth, the aggregate availablebandwidth between leaf Switch C 720 c and spine switch A 720 a is 30Gbps; between leaf switch C 720 c and spine switch A 720 a is 30 Gbps;and between leaf switch D 720 d and spine switch A 720 a is 30 Gbps.

It is noted that the embodiments described herein may be utilized withother communication speeds, such as 10 Gbps, 40 Gbps, 100 Gbps, andother values, as well as a with a different number of ports (e.g., 10,40, 100 ports, etc., although other values are also possible), as longas the principles presented are preserved. The embodiments illustratedshould therefore not be interpreted to be exclusive or limiting, butrather exemplary or illustrative.

Since the virtual network to has a limit of 20 Gbps, all thehost-to-switch bandwidth is within limits. The aggregate bandwidth fromswitch B to switch A is also within limits, but the aggregate bandwidthfrom switch D to switch A exceeds the limit causing the egress VTS 724 don switch D 720 d to drop 20 Gbps worth of traffic. Similarly, egressVTS 724 a on spine switch A 720 a will drop an additional 20 Gbps ofbandwidth, allowing the destination switch C to receive only 20 Gbps ofbandwidth.

If the spine switch was a simple switch without the VTS capability, theingress VTS on destination leaf switch C 720 c would have dropped theexcess packets allowing the bandwidth limits to be maintained. Theadvantage of having limits within the switches is that all decisions aremade on the individual VTS, and as long as the leaf or the TOR switchesenforce the bandwidth limits, the spine switches can be traditional besteffort switches.

The disadvantage of this scheme is that excess or unused resources atany given time can't be used by traffic needing the resources. SwitchesD, A, and C could have allowed 30 Gbps of bandwidth to go through sinceno one was using the bandwidth in this example.

FIG. 16B illustrates virtual networks with local bandwidth guaranteesspanning a hierarchy of switches. It is possible to use the switchesdescribed in FIG. 15, and allow the virtual network to have a guaranteedbandwidth of 20 Gbps. FIG. 16B shows a virtual network spanning ahierarchy of switches where the individual switches implement bandwidthcoherency control giving bandwidth guarantees instead of limits. Usingthe same assumptions as in FIG. 16A, switch D provides local bandwidthoptimizations, allowing 30 Gbps of traffic to flow through since thereis enough capacity.

Similarly, spine switch A allows 30 Gbps of traffic to leaf switch C.The point of control has shifted from the egress VTS 724 a to theingress VTS 722A on switch A, which proportionately drops packets comingfrom switches B and D. This flow control mechanism is better than thecontrol provided in FIG. 16A because the control is pushed closer to thesource.

FIG. 16C illustrates a virtual network with global bandwidth guaranteesspanning a hierarchy of switches, according to one embodiment. In anideal scenario, the global bandwidth guarantees to be implemented acrossthe hierarchy of switches. Continuing with the same scenario as in FIG.16A, FIG. 16C shows that the aggregate throughput achieved is 30 Gbps,but the control points have shifted closer to the source based onbandwidth coherency messages exchanged between the switches. This allowsthe 20 Gbps bandwidth to be available between switch B and switch A and10 Gbps to be available between switch D and switch A, which can be usedby other virtual networks.

In the case where the host is able to participate in the ndOS bandwidthcontrol, the flow control can be pushed all the way to the host allowingthe host to slow the application producing packets and possibly othermechanisms to avoid packet loss on the network.

FIG. 16D illustrates global bandwidth guarantees with a VTS leaf switchand a traditional spine switch, according to one embodiment. FIG. 16Dillustrates a layer 2 fabric with a mix of ndOS switches and traditionalswitches.

Spine switch A is a traditional switch without any virtualization or VTScapabilities. Host X wants to send a 6-Gbps packet stream to host Z, andhost Y wants to send a 7-Gbps packet stream to host Z. Additionally, itis assumed that all the lines have a physical capacity of 10 Gbps, thevirtual network to which virtual machines X, Y, and Z belong to has 5Gbps bandwidth guarantee, and there is no other activity on the network.

Under normal circumstances, switches B and D can send 6 and 7 Gbpsstreams to switch A. As long as switch A has enough capacity and isnon-blocking, switch A can send the combined 13 Gbps of bandwidth toswitch C using two of the links between switches A and C. At this point,switch C can only send 10 Gbps to host Z (because of the physical linkcapacity of 10 Gbps) and will have to drop the extra 3 Gbps. If instead,the bandwidth coherency controller (BCC) detects the flow constraint,the BCC can slow the ingress virtual queues corresponding to the linkbetween switches A and C. The ingress VOQ of switch C knows that theother side (switch A) is not VTS capable so it can instead generate anew message with a different MAC type to the source MAC address of thepackets causing the problem.

Switch A will still switch packets for switches B and D where they getcaptured due to the unique MAC type reserved for the control messages.This allows the BCC on switches B and D to adjust the drain rates foringress VOQ corresponding to hosts X and Y, and as such, only 5 Gbps isallowed to flow to switch A.

Further, is possible for the ingress VoQ on switches B and D to push theflow control to hosts X and Y and prevent any packet drops at all. TheVoQ on switches B and D can use 802.1qbb based PFC frames or any otherprotocol understood by hosts X and Y to accomplish this. It is notedthat that given the large number of virtual networks visible at thespine switches, it is not possible to use 802.1qbb PFC messages toaccomplish this entirely, but using the Bandwidth Coherency Messagebetween the leaf and the spine switches and PFC between the leafswitches and host, a truly lossless network offering global bandwidthguarantees can be created.

In the case of hierarchical switches offering global bandwidthguarantees for virtual networks, all switches need to implement ingressand egress VTS. In addition, the switches exchange messages during bootup, telling other switches or hosts that the switch has ndOScapabilities (e.g., sending a broadcast/multicast message that can beignored by non-VTS capable switches, but that VTS-capable switches willnote).

FIG. 17A shows a flowchart illustrating an algorithm for processingnetwork packets, in accordance with one embodiment. In operation 832, apacket is received at the switch module. The switch module has one ormore ports with a communications interface of a first type (CI1) and oneor more ports with a communications interface of a second type (CI2),where a server is in communication with the switch module via a firstCI2 coupling and a switch controller is in communication with the switchmodule via a second CI2 coupling. The server includes a virtual CI1driver that provides a CI1 interface to applications in the server, thevirtual CI1 driver defined to exchange CI1 packets with the switchmodule via the first CI2 coupling. The virtual CI1 driver furtherincludes a first network device operating system (ndOS) program, and theswitch controller includes a second ndOS program that, when executed bya processor, controls packet switching policy in the switch module. Thepacket switching policy includes a definition for switching incomingpackets through the switch module or through the switch controller. Thefirst ndOS program and the second ndOS program, when executed byrespective processors, exchange control messages to maintain a networkpolicy for a layer 2 switch fabric.

From operation 832, the method flows to operation 834 for determining,by a classifier in the switch module, to switch the packet through theswitch module or through the switch controller based on the packetswitching policy.

From operation 834, the method flows to operation 836 where the packetis switched based on the determination made in operation 834.

FIG. 17B shows a flowchart illustrating an algorithm for networkingcommunications, in accordance with one embodiment. In operation 852, apacket is received in a first format by a virtual driver providing acommunications interface of a first type (CI1), the first format beingfor CI1.

From operation 852, the method flows to operation 854 where the packetis encapsulated in a second format by a processor. The second format isfor a communications interface of a second type (CI2) different fromCI1.

From operation 854, the method flows to operation 856 where theencapsulated packet in the second format is sent to a switch module. Theswitch module includes a switch fabric, one or more CI1 ports and one ormore CI2 ports, and the switch module transforms the packet back to thefirst format to send the packet in the first format to a CI1 network viaone of the CI1 ports in the switch module.

In one embodiment, the virtual driver is defined to support more thanone virtual network interface card (VNIC). In another embodiment, thevirtual driver is defined to create a VNIC for a hypervisor.

In another embodiment, sending the encapsulated packet further includesselecting one of the CI1 ports based on a media access control (MAC)address of the packet.

In yet another embodiment, the switch module further includes a networkdevice operating system (ndOS) program for exchanging switchinginformation with other switches in a switch layer fabric.

In one embodiment, sending the encapsulated packet further includesadding virtual network (VLAN) information to the packet before sendingthe packet.

In one embodiment, CI1 is Ethernet and CI2 is Peripheral ComponentInterconnect Express (PCI). In one embodiment, CI2 can be a specifictype of PCI, such as PCIe (Peripheral Component Interconnect Express),or other versions. In some embodiments, other combinations ofcommunications interfaces are also possible, as long as the principlespresented herein are utilized. For example, each of the communicationsinterface may be one of Ethernet, Peripheral Component Interconnect(PCI) (which may be any Peripheral Component Interconnect, such as PCI,Peripheral Component Interconnect Express (PCIe), Peripheral ComponentInterconnect eXtended (PCI-X)), Accelerated Graphics Port (AGP), SerialATA (SATA), AT Attachment (ATA), Serial Attached SCSI (SAS), SmallComputer System Interface (SCSI), High-Definition Multimedia Interface(HDMI), etc. Any combination can be used, so long as the translationbetween the types of communications interfaces result in providing thefunctionality to the ndOS and switch circuitry, hardware, etc.,firmware, combinations of hardware and software, cloud based servicesthat interact with the hardware or software to enable virtual loadbalance and discovery of other ndOS switches, etc.

FIG. 17C shows a flowchart illustrating an algorithm for switching anetwork packet, in accordance with one embodiment. In operation 872, apacket, having a media access control (MAC) address, is received.

From operation 872, the method flows to operation 874 where the packetis switched by a first packet switching device (PSD) when the MACaddress is present in a first memory. From operation 874, the methodflows to operation 876 where the packet is transferred to a second PSDwhen the MAC address is absent from the first memory and present in asecond memory associated with the second PSD.

From operation 876, the method flows to operation 878 where the packetis transferred to a third PSD when the MAC address is absent from thefirst memory and the second memory.

In one embodiment, the first memory has a smaller size than the secondmemory and the second memory has a smaller size than a third memorycoupled to the third PSD.

In one embodiment, a first access time of the first memory is less thana third access time of the third memory, and a second access time of thesecond memory is less than the third access time.

In another embodiment, the first memory is a ternary content addressablememory (TCAM). In one embodiment, the first PSD is a switch fabric.

In one embodiment, the second PSD is a packet processor and the thirdPSD is a processor.

In another embodiment, information about the MAC address is added if theMAC address was absent from the first memory.

In one embodiment, an address discovery is performed when the MACaddress is absent from the first, second, and third memories.

FIG. 17D shows a flowchart illustrating an algorithm for providing aprogram to a server, in accordance with one embodiment. In operation882, a request is received by a switching device from a first server,the request being for a boot image for booting the first server. Fromoperation 882, the method flows to operation 884 where a determinationis made whether the boot image is available from non-volatile storage inthe switching device.

From operation 884, the method flows to operation 886 where the requestis forwarded to a second server when the boot image is absent from thenon-volatile storage. From operation 886, the method flows to operation888 where the boot image is sent to the first server from the switchingdevice when the boot image is available from the non-volatile storage.

In one embodiment, the request is a Preboot eXecution Environment (PXE)boot request.

In another embodiment, the request is addressed to a second server inthe switching device intercepts the request to serve the boot imagewithout sending the request to the second server.

Inject another embodiment, a PXE redirection service request (ProxyDHCP) is received for a boot image server, and a response to the PXEredirection service request is sent with an address of the switchingdevice.

In one embodiment, the switching device is defined to intercept bootimage requests from systems directly coupled to the switching device.

In another embodiment, the switching device is defined to intercept bootimage requests when the switching device is in a network path betweenthe first server and a second server providing boot images.

In yet another embodiment, a a dynamic host configuration protocol(DHCP) request is detected, and a response is sent to the DHCP requestby the switching device when the switching device has information tosatisfy the DHCP request.

In one more embodiment, an address resolution protocol (ARP) request isreceived, and a response to the ARP request is sent by the switchingdevice.

In one embodiment, a request for a software driver is detected, and aresponse is sent for the software driver by the switching device whenthe software driver is available in the non-volatile storage.

In yet another embodiment, a request for an application programming codeis detected, and a response to the request is sent for the applicationprogram code by the switching device when the application program codeis available in the non-volatile storage.

In one more embodiment, a request is detected for an application upgradeprogram code, and a response to the request is sent for the applicationupgrade program code by the switching device when the applicationupgrade program code is available in the non-volatile storage.

FIG. 17E shows a flowchart illustrating an algorithm for managing aswitching layer fabric, in accordance with one embodiment. In operation890, a first ndOS program executing in a first ndOS switching deviceexchanges a switching policy regarding the switching of network packetsin a plurality of ndOS switching devices, each ndOS switching devicehaving a respective ndOS program executing therein, and the switchingpolicy is exchanged with other ndOS programs via multicast messages.

From operation 890, the method flows to operation 892 where resourcecontrol messages are exchanged with the other ndOS switching devices toimplement service level agreements in the switching layer fabric, wherethe ndOS switching devices cooperate to enforce the service levelagreements.

From operation 892, the method flows to operation 894 where changes arereceived to the switching policy. From operation 894, the method flowsto operation 896 when the received changes to the switching policy arepropagated via message exchange between the ndOS programs, where thendOS switching devices are managed as a single logical switch that spansthe plurality of ndOS switching devices.

Embodiments of the present disclosure may be practiced with variouscomputer system configurations including hand-held devices,microprocessor systems, microprocessor-based or programmable consumerelectronics, minicomputers, mainframe computers and the like. Theembodiments can also be practiced in distributed computing environmentswhere tasks are performed by remote processing devices that are linkedthrough a network.

With the above embodiments in mind, it should be understood that theembodiments can employ various computer-implemented operations involvingdata stored in computer systems. These operations are those requiringphysical manipulation of physical quantities. Any of the operationsdescribed herein are useful machine operations. The e also relates to adevice or an apparatus for performing these operations. The apparatusmay be specially constructed for the required purpose, such as a specialpurpose computer. When defined as a special purpose computer, thecomputer can also perform other processing, program execution orroutines that are not part of the special purpose, while still beingcapable of operating for the special purpose. Alternatively, theoperations may be processed by a general purpose computer selectivelyactivated or configured by one or more computer programs stored in thecomputer memory, cache, or obtained over a network. When data isobtained over a network the data may be processed by other computers onthe network, e.g., a cloud of computing resources.

One or more embodiments can also be fabricated as computer readable codeon a non-transitory computer readable storage medium. The non-transitorycomputer readable storage medium is any non-transitory data storagedevice that can store data, which can be thereafter be read by acomputer system. Examples of the non-transitory computer readablestorage medium include hard drives, network attached storage (NAS),read-only memory, random-access memory, CD-ROMs, CD-Rs, CD-RWs, magnetictapes and other optical and non-optical data storage devices. Thenon-transitory computer readable storage medium can include computerreadable storage medium distributed over a network-coupled computersystem so that the computer readable code is stored and executed in adistributed fashion.

Although the method operations were described in a specific order, itshould be understood that other housekeeping operations may be performedin between operations, or operations may be adjusted so that they occurat slightly different times, or may be distributed in a system whichallows the occurrence of the processing operations at various intervalsassociated with the processing, as long as the processing of the overlayoperations are performed in the desired way.

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, it will be apparent thatcertain changes and modifications can be practiced within the scope ofthe appended claims. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the embodiments arenot to be limited to the details given herein, but may be modifiedwithin the scope and equivalents of the appended claims.

What is claimed is:
 1. A method comprising: storing one or more bootimages in non-volatile storage of a switching controller in a networkcomputing device, the network computing device including a first server,a switch module, and the switching controller, wherein the switch moduleprovides, to the first server, access to a network, wherein theswitching controller is in local communication with the switch module;receiving, at the switching controller, a redirection service requestfor a boot image server; responding, by the switching controller, to theredirection service request with an address of the switching controller;receiving a request at the switching controller from the first serverfor a boot image for booting the first server; determining if the bootimage is available from the non-volatile storage in the switchingcontroller; forwarding the request to a second server when the bootimage is absent from the non-volatile storage; and sending the bootimage to the first server from the switching controller when the bootimage is available from the non-volatile storage, wherein the boot imageis sent without accessing the network outside of the network computingdevice, wherein operations of the method are executed by a processor. 2.The method as recited in claim 1, wherein the redirection servicerequest is a Preboot eXecution Environment (PXE) redirection servicerequest, wherein the request is a Preboot eXecution Environment (PXE)boot request.
 3. The method as recited in claim 1, wherein the requestis addressed to the second server and the switching controllerintercepts the request to serve the boot image without sending therequest to the second server.
 4. The method as recited in claim 1,wherein the switching controller is defined to intercept boot imagerequests from servers in the network computing device.
 5. The method asrecited in claim 1, further including: detecting a dynamic hostconfiguration protocol (DHCP) request; and responding to the DHCPrequest by the switching controller when the switching controller hasinformation to satisfy the DHCP request.
 6. The method as recited inclaim 1, further including: detecting an address resolution protocol(ARP) request; and responding to the ARP request by the switchingcontroller.
 7. The method as recited in claim 1, further including:detecting a request for a software driver; and responding to the requestfor the software driver by the switching controller when the softwaredriver is available in the non-volatile storage.
 8. The method asrecited in claim 1, further including: detecting a request for anapplication program code; and responding to the request for theapplication program code by the switching controller when theapplication program code is available in the non-volatile storage. 9.The method as recited in claim 1, further including: detecting a requestfor an application upgrade program code; and responding to the requestfor the application upgrade program code by the switching controllerwhen the application upgrade program code is available in thenon-volatile storage.
 10. The method as recited in claim 1, furtherincluding: receiving, at the switching controller, the boot image from asecond switching controller before sending the boot image to the firstserver, wherein the second switching controller is configured to serveboot images.
 11. The method as recited in claim 1, wherein the switchingcontroller is configured to detect one or more hypervisors executing inthe first server.
 12. The method as recited in claim 1, wherein theswitching controller is configured to reboot a hypervisor executing inthe first server.
 13. A switching controller comprising: a non-volatilememory having one or more boot images; a volatile memory having acomputer program; a switch fabric; and a processor coupled to thenon-volatile memory, the volatile memory, and the switch fabric, whereinthe switching controller is in a network computing device that furtherincludes a first server and a switch module, wherein the computerprogram, when executed by the processor, performs a method comprising:receiving from the first server a redirection service request for a bootimage server; responding to the redirection service request with anaddress of the switching controller; receiving a request by the switchfabric from the first server, the request being addressed to a secondserver, the request being for a first boot image for the first server;determining if the first boot image is available in non-volatile memory;forwarding the request to the second server when the boot image isabsent from the non-volatile memory; and sending the first boot image tothe first server when the first boot image is available from thenon-volatile memory, wherein the boot image is sent without accessingthe network outside of the network computing device.
 14. The switchingcontroller as recited in claim 13, wherein the redirection servicerequest is a Preboot eXecution Environment (PXE) redirection servicerequest, wherein the request is a Preboot eXecution Environment (PXE)boot request.
 15. The switching controller as recited in claim 13,wherein the switching controller is defined to intercept boot imagerequests from servers in the network computing device.
 16. The switchingcontroller as recited in claim 13, wherein the switching controller isdefined to intercept boot image requests when the switching controlleris in a network path between the first server and a second serverproviding boot images.
 17. The switching controller as recited in claim13, wherein the processor is operable to receive the boot image from asecond switching controller before sending the boot image to the firstserver, wherein the second switching controller is configured to serveboot images.
 18. A computer program embedded in a non-transitorycomputer-readable storage medium, when executed by one or moreprocessors, the computer program comprising: program instructions forstoring one or more boot images in non-volatile storage of a switchingcontroller in a network computing device, the network computing deviceincluding a first server, a switch module, and the switching controller,wherein the switch module provides, to the first server, access to anetwork, wherein the switching controller is in local communication withthe switch module; program instructions for receiving, at the switchingcontroller, a redirection service request for a boot image server;program instructions for responding, by the switching controller, to theredirection service request with an address of the switching controller;program instructions for receiving a request at the switching controllerfrom the first server, the request being addressed to a second server,the request being for a boot image for the first server; programinstructions for determining if the boot image is available from thenon-volatile storage in the switching controller; program instructionsfor forwarding the request to the second server when the boot image isabsent from the non-volatile storage; and program instructions forsending the boot image to the first server from the switching controllerwhen the boot image is available from the non-volatile storage, whereinthe boot image is sent without accessing the network outside of thenetwork computing device.
 19. The computer program as recited in claim18, wherein the redirection service request is a Preboot eXecutionEnvironment (PXE) redirection service request, wherein the request is aPreboot eXecution Environment (PXE) boot request.
 20. The computerprogram as recited in claim 18, wherein the switching controller isdefined to intercept boot image requests from servers in the networkcomputing device.